No, its obviously not just everyone else's fault. Whose fault it is, is honestly irrelevant. What's relevant is that we allow this sort of thing to happen. "Bad" people don't just spawn from nothing, there's always some underlying issue that could get fixed. To say that the fact most of these people have issues that they aren't able to control by themselves, and the fact that they become "bad" is purely coincidental, is just people trying to find a easy way out of problems. Its easy to just say "he's an evil person" and leave it at that, but that won't stop other "evil" people from appearing.

We need to find the root problem, and as I said, there seems to be a common denominator in all of this. So we have two choices:

1. Keep blaming people's behaviours solely on themselves and allow them to keep hurting others, physically or verbally.
2. Realize that we systematically ignore and isolate "wierd" people which allows them to ferment into monsters, and then we actually start trying to fix the problem.

Telling them that they are solely at fault isn't going to help anybody. They won't get help just because they COULD possibly fix things.

If you don't want to help these people, at least we should try to prevent them from developing these personalities in the first place. Diagnose mental problems as soon as possible. Improve mental help mechanisms. Improve sexual education. Take bullying seriously.