Worst, add sociopath on top of it

You'd love Political Ponerology. It's a book about just that.

I dated a girl that was diagnosed as a narcissist. It was brutal but I still felt that the government was worse.

What separates a diagnosed narcissist from people with narcissistic traits that we probably all have?

A narcissist never figured out that you can't force others to play according to your rules, and spend their entire lives attempting to control and manipulate others. Normal people are mildly selfish, but able to get along just fine.

Good question. It’s always the degree of those traits. For example, narcissists struggle to empathize with the feelings and needs of others. To some degree all humans struggle with that: we can never know exactly what someone’s feelings are. But if someone began crying in front of you because they said that you hurt them, you’d feel bad. A narcissist may not feel bad and may actually attack you (e.g. gaslighting). Seeing someone cry in front of them may elicit a defensive response instead of an empathic one.