People need to hate someone. Especially someone who is known, but not recognized by the majority of the public as evil, like Hitler, because it would be uninteresting. People want to hate those who act under the guise of a good guy, but not obvious hypocrites (like prominent politicians), but those who seem to be really closer to the good side.

The idea is similar to conspiracy theories - a person gets the feeling that he does not allow himself to be deceived and this elevates him above others