I've figured it out. The reason a Trump fan can't be convinced that he is a bad man is because they know he is a bad man. That's what they like about him. He is condescending, rude, and mean and they are hoping to project their own anger through him.
Demagogue- noun: a political leader who tries to get support by making false claims and promises and using arguments based on emotion rather than reason.
"Hey jackass, get your government off my freedom." MOLON LABE
