Sunk Cost Fallacy

The sunk cost fallacy is a cognitive bias in which people feel compelled to continue a course of action because they have already invested resources (money, time, or effort) that cannot be recovered, rather than making a forward-looking decision based on expected future outcomes. In economics, a sunk cost is any past expense that has already been incurred and cannot be recouped regardless of what you decide to do next.

In personal finance, the sunk cost fallacy appears in many forms. You might hold onto a losing investment because you cannot bear to "lock in" the loss by selling, even though the funds could be more productively invested elsewhere. You might continue paying for a gym membership you never use because you already signed up. You might resist selling a home at a loss even when the financial math favors moving on. In each case, the past expenditure is irrelevant to the optimal decision going forward.

Business owners may be particularly susceptible to the sunk cost fallacy. After investing years of effort and substantial capital into a business line or strategy that is not working, it can be emotionally difficult to change course or cut losses. The rational approach is to evaluate each decision based on its expected future return, not on what has already been spent.

One practical way to combat the sunk cost fallacy is to ask yourself: "If I were starting fresh today, with no prior investment, would I make the same choice?" If the answer is no, the sunk cost may be influencing your decision. Another approach is to set predefined criteria for when to exit an investment, project, or commitment, which removes emotion from the decision in the moment.

Understanding the sunk cost fallacy does not mean you should abandon every underperforming investment or half-finished project. Sometimes patience and persistence are warranted. The key is to distinguish between a decision to continue based on sound future expectations and one driven primarily by reluctance to accept a past loss.