People are often greedy. Instead of getting out when they're ahead, they get sucked into the "sunk cost fallacy", where they've invested so much time/money that

People are often greedy. Instead of getting out when they're ahead, they get sucked into the "sunk cost fallacy", where they've invested so much time/money that they feel like they must see it through to completion. I've noticed this in myself throughout my life from time to time.