Actually ... that's a fallacy.
"Bad" people do "bad" things for the same reason "good" people do "good" things.
Because they think they are doing something "good".
VERY RARELY does anyone think they are "bad", or do what they do due to "bad intentions".
Villains do not think they are villains.
Remember ... "good" and "bad" are artificial concepts, and entirely dependent on the whims of society and culture.