I think at the level of people like Donald Trump we're talking about a full-blown sociopath. Narcissism isn't so much about gazing into a still pond, enthralled by your own reflection as it is an inherent lack of capacity to perceive anything outside of yourself as real. Everybody's the star of their own movie to one extent or other, but some people take that a little further than they should, and can become insanely violent when their dream self-identity is challenged.
My mother worked for a time at the Camarillo State Mental Hospital, and she told me the probably apocryphal story about the two mental patients who both thought they were Jesus Christ. "So, what happened when they met?" one doctor asks. "They fought like wild animals," the other replies. "Carnage. Absolute carnage."
