Why is there a link between stupidity and being evil? I understand this is a loaded question but I think the assumption can withstand scrutiny. Dumber people tend to be more malicious and more intelligent people tend to be more peaceful and mellow.

If you don't agree with the premise, you can say why. I understand there's evil geniuses (I think Marx was one) but I think dumber people in general tend to be more evil. Why?