In both behavioral finance and psychology, there is a concept known as the "sunk cost fallacy". This term refers to an individual's tendency to follow through with something that they've already started, be it time, money, or general energy.
For teenagers, the sunk cost fallacy can be displayed in relationships with a friend or a loved one. Hanging onto a significant other who you are no longer interested in is quite common. Those in the workforce may stay with a job for too long because they're comfortable and have established a certain status level. Those in finance may stick with a stock because its value could go back up.