Money Already Spent

The sunk cost fallacy is our irrational tendency to keep investing in something because of what we already spent, instead of judging its future prospects honestly. The money is already gone, yet it pulls every decision that follows.

You sit through a terrible movie because you paid for the ticket. You finish a bad meal because money was spent on it. You keep a gym membership you never use, because canceling means admitting the purchase was a mistake.