Winning feels good, and the more humiliating it is for your foe, the greater the satisfaction. Who cares about good sportsmanship and "being big about it"? Forget giving that cardboard villain who kidnapped the princess a Last Second Chance, you just want to grind that Smug Snake's head into the earth in the most soul-crushingly cheap way possible for all the grief he's caused you. Or because you can. Both are good reasons, really!