The result, and the taboo method gives a thrill. It's a power trip essentially. It is also used to close the perceived skill gap, or get revenge. Some people enjoy a very uneven power balance - in games, this means that they like to get an overwhelming win, or "stomp". Sometimes skilled people achieve this by playing in a league that is much less skilled than their own, "smurfing". Technically not cheating, but it's usually against the EULA, and creates essentially the same situation.

All in all, it's just power dynamics, and lack of compassion.