Why People Make Irrational Financial Decisions

Traditional economic theory tends to assume that people make rational decisions. Faced with different choices, individuals are expected to weigh the costs and benefits, assess the available information and select the option that maximises their welfare.

Real life is considerably messier.

People hold losing investments for too long, sell successful investments too early, spend more when paying by card than when using cash, follow speculative markets because everyone else appears to be making money, and sometimes avoid investing altogether because markets feel intimidating.

These decisions are not necessarily the result of poor intelligence or insufficient financial knowledge. They often reflect the way human beings naturally process uncertainty, risk and emotion.

Understanding those tendencies is one of the most important parts of becoming a better investor.

Financial Decisions Are Emotional Decisions

Money carries meaning beyond its purchasing power.

It can represent security, freedom, status, achievement or even fear. A £10,000 investment loss therefore does not necessarily feel like a simple reduction in net worth. Depending on the person, it may feel like lost security, failure or a threat to future plans.

That emotional dimension matters because financial decisions are frequently made under conditions of uncertainty.

Investors rarely know exactly what a company will earn five years from now. Consumers cannot perfectly predict future inflation. Homebuyers do not know precisely where property prices will go. Entrepreneurs cannot know with certainty whether their businesses will succeed.

When outcomes are uncertain, people rely increasingly on instincts and mental shortcuts.

Those shortcuts can be useful. They allow individuals to make decisions quickly without analysing every possible variable.

But they can also produce systematic mistakes.

Losses Hurt More Than Equivalent Gains Feel Good

One of the most powerful ideas in behavioural finance is loss aversion.

People generally experience losses more intensely than equivalent gains.

The satisfaction of making £1,000 does not necessarily compensate emotionally for the pain of losing £1,000.

That imbalance can influence investment behaviour in several ways.

An investor who owns a share that has fallen significantly may refuse to sell because doing so would crystallise the loss. Instead, they continue holding the investment—not because the investment case remains attractive, but because selling would force them to admit that the original decision was wrong.

The purchase price gradually becomes psychologically important even though the market does not care what the investor originally paid.

The correct question should be:

Would I buy this investment today at its current price?

Instead, investors frequently ask:

When will it return to the price I paid?

These are very different questions.

Loss aversion can therefore turn what should be a forward-looking investment decision into an emotional attempt to recover the past.

Investors Become Attached to Their Original Decisions

Closely related to loss aversion is anchoring.

People often become overly influenced by the first piece of information they encounter.

In investing, that anchor could be a previous share price, an analyst's price target, a company's historical valuation or the investor's own purchase price.

Suppose a company once traded at £100 per share and later falls to £60.

Investors may instinctively view £60 as cheap because the share previously traded at £100.

But the company's earnings prospects, competitive position or balance sheet may have deteriorated materially.

The previous price does not establish intrinsic value.

The same problem occurs when investors become anchored to optimistic forecasts. If someone originally believed that a company would generate £5 billion in revenue, they may continue interpreting new information through that assumption even after evidence begins suggesting that the forecast is unrealistic.

Rather than updating their view, they search for reasons why their original thesis might eventually prove correct.

People Prefer Information That Confirms What They Already Believe

This leads to another important behavioural tendency: confirmation bias.

Once people form an opinion, they tend to notice information that supports it and discount evidence that challenges it.

An investor who believes strongly in an electric vehicle company may enthusiastically share evidence of growing EV adoption while dismissing falling margins, increasing competition or weak cash generation.

Someone bearish on the same company may do the opposite.

Both investors can look at identical information and walk away more convinced of their original positions.

Modern information environments can make this worse.

Investors can easily surround themselves with analysts, social-media accounts, newsletters and online communities that reinforce their existing beliefs. What appears to be extensive research can sometimes become sophisticated confirmation bias.

Good investing requires actively searching for evidence that could prove your thesis wrong.

The objective should not be to defend an investment idea.

It should be to determine whether the idea remains correct.

Overconfidence Makes Investors Underestimate Risk

Most people naturally believe their judgement is better than average.

In financial markets, this can become expensive.

A few successful investments can quickly convince someone that they possess exceptional stock-picking ability. They may begin trading more frequently, concentrating their portfolio or using leverage because recent success has increased their confidence.

But investment outcomes are influenced by both skill and randomness.

An investor who buys five technology stocks shortly before a sector-wide rally may generate excellent returns without necessarily having demonstrated exceptional company analysis.

The danger appears when temporary success is interpreted as permanent skill.

Overconfidence can cause investors to underestimate uncertainty, ignore downside scenarios and take positions that are significantly larger than their actual knowledge justifies.

The strongest investors are therefore not necessarily those with the strongest opinions.

They are often those who understand precisely where their knowledge ends.

People Follow Crowds Because Crowds Feel Safer

Financial markets repeatedly demonstrate the power of herding behaviour.

When an asset rises rapidly and large numbers of people begin discussing it, staying on the sidelines can become psychologically uncomfortable.

The investor is no longer simply evaluating an asset.

They are watching other people apparently become wealthier.

That creates fear of missing out.

The irony is that an investment can feel psychologically safest precisely when it is financially most dangerous. Rising prices, widespread optimism and positive media coverage can create the impression that risk has disappeared.

Meanwhile, genuinely attractive opportunities often appear when sentiment is poor and buying feels uncomfortable.

Crowds provide emotional reassurance.

But markets reward future cash flows, not social consensus.

An investment does not become attractive simply because large numbers of people want to own it.

Sometimes popularity is evidence that much of the optimism is already reflected in the price.

Recent Events Feel More Important Than They Really Are

People also tend to overweight recent experiences.

This is sometimes described as recency bias.

After several years of strong stock-market performance, investors can begin assuming that strong returns are normal. After a major market crash, the opposite occurs: investors may become excessively cautious because falling markets remain fresh in their memories.

The same behaviour occurs across the economy.

Consumers who have recently experienced high inflation may continue expecting rapid price increases even after inflation begins slowing. Property investors may assume house prices will continue rising because they have done so for several years.

Recent events are vivid.

Long-term historical patterns are less emotionally powerful.

But investing often requires distinguishing between temporary conditions and structural realities.

People Treat Money Differently Depending on Where It Came From

Another surprisingly common behaviour is mental accounting.

Economically, £1,000 is £1,000.

Psychologically, people frequently treat money differently depending on its source.

Someone may carefully protect £1,000 of salary while spending a £1,000 bonus much more freely.

An investor may take excessive risks with profits because they regard them as "house money", even though those profits are now part of their wealth.

Consumers may simultaneously carry expensive credit-card debt while refusing to touch money held in a savings account because the savings have been mentally allocated to another purpose.

Creating separate budgets can be useful.

The problem arises when psychological categories cause people to ignore the true economic relationship between assets, liabilities and spending decisions.

We Prefer Immediate Rewards to Distant Benefits

Many poor financial decisions are ultimately battles between the present and the future.

Saving for retirement offers a significant future benefit.

Spending the money today provides immediate satisfaction.

Humans have a natural tendency to give disproportionate weight to immediate rewards. Economists often describe this as present bias.

It helps explain why people procrastinate over pension contributions, emergency savings and long-term investing despite understanding their importance.

The costs are immediate.

The benefits are distant.

This is why good financial systems often rely on automation.

Automatically transferring money into savings or investments removes the need to repeatedly make the same disciplined decision.

Behavioural design can sometimes be more effective than willpower.

Complexity Encourages Inaction

Not every irrational financial decision involves taking excessive risk.

Sometimes the mistake is doing nothing.

Financial markets can appear enormously complicated. Investors face thousands of securities, competing economic forecasts, valuation methods, tax considerations and endless financial commentary.

Faced with too many options, people can experience choice paralysis.

They postpone opening an investment account.

They leave cash uninvested for years.

They continually research without ever taking action.

Ironically, the search for the perfect decision can prevent someone from making a reasonably good decision.

For many investors, a simple diversified strategy executed consistently will ultimately be more valuable than a theoretically perfect strategy that is never implemented.

Intelligence Does Not Eliminate Behavioural Bias

One of the most important lessons of behavioural finance is that knowing about biases does not automatically make someone immune to them.

Professional investors experience fear.

Fund managers can become overconfident.

Analysts can become attached to their forecasts.

Executives can continue funding unsuccessful projects because they have already invested enormous amounts of money into them.

Expertise can occasionally make biases more dangerous because sophisticated individuals are better able to construct convincing arguments supporting decisions they already want to make.

The objective should therefore not be to eliminate emotion entirely.

That is unrealistic.

The objective is to create processes that reduce the influence of emotion when important decisions are being made.

Better Financial Decisions Require Better Systems

Investors can reduce behavioural mistakes by creating rules before emotions become involved.

An investment thesis can be written before purchasing a stock, including the reasons for buying, the risks and the conditions that would invalidate the thesis.

Portfolio limits can prevent excessive concentration.

Regular investment contributions can reduce attempts to perfectly time the market.

Valuation ranges can stop investors from chasing rapidly rising assets.

Investment journals can reveal whether decisions were based on sound reasoning or simply produced favourable outcomes through luck.

The central principle is simple:

Do not rely entirely on how you expect yourself to behave under pressure. Build a system that makes good behaviour easier.

The Bigger Lesson

Financial markets are often presented as exercises in mathematics.

Valuation models matter. Accounting matters. Economics matters.

But investors are still human beings interpreting those numbers.

Fear can make a cheap asset look dangerous. Greed can make an expensive asset look safe. Confidence can disguise uncertainty. Social pressure can turn speculation into something that feels rational.

Understanding finance therefore requires understanding behaviour.

The investor who recognises their own psychological weaknesses gains an important advantage—not because they will always make rational decisions, but because they become better equipped to identify when emotion is beginning to replace analysis.

Markets may be driven by numbers.

But the people making the decisions are not.