The Sunk Cost Fallacy: Why You Finish Bad Movies and Stay in Bad Jobs

You're an hour into a terrible movie. You're not enjoying it. But you think: "I already paid for the ticket, so I might as well finish it." Congratulations — you've just fallen for the sunk cost fallacy. The money is gone whether you stay or leave. The only rational question is: "Will the next hour be worth my time?" But your brain can't let go of what it already invested.

The sunk cost fallacy scales up terrifyingly. Companies pour billions into failing projects because they've "already invested too much to stop." Governments continue wars because withdrawing would mean soldiers "died for nothing." People stay in miserable relationships because they've "already given it five years." In each case, past investment — which cannot be recovered — is driving future decisions that should be based only on expected future value.

Economists call unrecoverable past costs "sunk costs" precisely because they should sink out of your decision-making. The antidote is a mental exercise called the "clean slate" test: if you were starting from scratch today, with no prior investment, would you choose this project/relationship/movie? If not, the only thing keeping you there is the fallacy. The best time to quit is when continuing costs more than it returns — regardless of what you've already spent.