Loss Aversion

The tendency to prefer avoiding losses over acquiring equivalent gains.

An investor refuses to sell a stock that has dropped 30% in value, hoping it will recover, while quickly selling stocks that have gained even small amounts. The pain of realizing a loss prevents rational portfolio management, while gains are locked in prematurely.
A customer keeps a subscription service they barely use because canceling feels like losing something, even though the money saved would be more valuable. The psychological loss of cancellation outweighs the financial gain of saving money.

Note

Central concept in Prospect Theory, developed by Daniel Kahneman and Amos Tversky, which won Kahneman the 2002 Nobel Prize in Economics.

This is a common bias