Attractive men seem to usually date women who are average looking if not slightly below average, while not-so-attractive men tend to gun for attractive women.

I think that it is this way because Attractive men are already satisfied with themselves. They are already confident in their worth so they look for compatibility instead of looks. It could also be said that a narcissistic attractive man may actually want less attractive women since they take less attention away from them and they fear they hold less power in a relationship dynamic than usual (they're basically intimidated by attractive women on their level).

On the other hand, it's mostly the mediocre men who don't have a lot things going on for them will mostly be obsessed with getting attractive girlfriend at times they will actually succeed because the lengths they will go to compensate for their looks. They are insecure about themselves, and the thought of having a pretty girl around their arms boosts their ego even if they do not realize it.