They get a thrill out of the capability or power to control other people through emotional abuse, some are sadists and thoroughly enjoy the mere feeling of manipulative jurisdiction.
It depends if we're talking of an awfully mean person, sometimes when you get the upper-hand on someone so corrupt then you can't help but take advantage of it but if its towards someone who is doing nothing absolutely wrong then thats just bad.
Cause we re inherently selfish
Deity complex They think they rule the WORLD BWHAhahahahahahaha.
because it's fun.