Due to how obvious it often is that a person is cheating, and that they really don't seem to care or even wear it like a badge, it doesn't appear to me that winning or getting a free trophy is really the reason in most cases.
I think it's more taking the win away from someone else, being a troll basically. Getting a high from messing up other people's day, because if you can't win, at least you can have fun being a little bitch to everyone else, and getting off on that power that their game is ruined because of you and there's nothing they can do. It's completely consistent with a criminal mindset.