You could argue there’s no such thing as a “terrible person”, we are all at the mercy of our sensory inputs and the innate properties of our neurons. In order to keep society functional we need to enforce boundaries on human behavior, and in some cases label people as untrustworthy and possibly lock them up to stop them from doing more damage. If “terrible person” is the wrong label, we could pick a different one.

Yes they do. They show classic narcissistic and sociopathic behaviors.