Do you know when you're ahead? Can you quit when you win or do you keep going on until all is gone? Why do folks do that so often?

Is it a death wish figuratively? Do they think they don't deserve to win and so go out of their way to insure failure subconsciously or perhaps even consciously? It's really puzzling. Or is it just GREED and their lust for MORE which grows larger and can never be sated? People are really crazy nuts sometimes. Nature or nurture?