Individuals, businesses and governments fall into the sunk cost trap when they base their decisions on past behavior and a desire to not waste the time or money they have already spent, instead of cutting their losses and making the decision that would give them the best outcome going forward. People are reluctant to admit, even to themselves, that they have wasted resources on a past decision. Changing directions is viewed, perhaps only subconsciously, as admitting failure. As a result, people tend to stay the course or even invest additional resources in a bad decision in a futile attempt to make their initial decision seem worthwhile.
Here is an example of the sunk cost trap in action:
Jennifer buys3 $1,000 worth of Company X’s stock in January. In December, its value has dropped to $100 even though the overall market and similar stocks have risen in value over the year. Instead of selling the stock and putting that $100 into a different stock that is likely to rise in value, she holds on to Company X’s stock, which in the coming months becomes worthless.