Same here, and for approximately the same reason (I left her because of the broken trust, she tried to get me back with a plan to fuck with me but I was already too fucked up over it).
It wasn’t my final relationship, but I’ll die alone and pretty happy. I have a couple of people that I actually trust and, same as you, a butt load of acquaintances that I enjoy being around. I generally use “friend” as shorthand for those people, but they’ll never really know me.
I’m very up front about relationships having a shelf life.
I’m not the one you asked, but I have a wild ass guess. It makes them feel important and/or powerful to have someone to look down on.