To me, evil is when you know the thing you're doing is morally wrong, you have the option to do anything else (including doing nothing at all) and you do it anyway.

I can make space for people who were trained on bad behavior.

I can make space for people doing the best they can in bad situations.

But I have met people who looked "normal" and could have easily not done the bad thing they were doing to someone else.

When you call them out, some will get defensive. They still have shame.

But the evil ones had this look like a child who knew they were getting away with something. And the something was hurting someone else.