It's a matter of dominance, and comfort. They lower you verbally because it keeps them above you, it makes them feel better than you are. And in a way, it does mean that they're better than you are, because you don't do anything to make them stop treating you like shit. We're animals after all, and in nature you'd get beaten into submission or death. Hell in prison you'd be everyone's butt-fuck slave and it wouldn't all be about homosexuality.
And it's a matter of comfort because if a good-looking girl dated a guy who they thought was ugly or below her league, their whole perception of women, dating and of their own personal worth would have to be questioned. In their eyes, their worth is equal to their looks, so as long as they have the face they have they don't have to make any effort towards being desirable mentally. And they use you as a sort of measure of that. The lower they keep you and the further away from desirable women, the more they can revel in their own superiority.
Let me tell you why my friend. Let me tell you why. First off... you ain't ugly. Now I"M UGLY. I would love to have your face on my face. Second. Guys are COMBATIVE. If they think you're competition, then they will put you down, insult you, ridicule you, or make fun of you, to make their self-esteem higher, and eliminate competition. Now they do this subconciously of course, they don't realize they're being COMBATIVE but they are. You should be flattered. It means you have a one up on them. ;)
Guys most of the time tell my I am ugly but what do they know it matters what the opposite gender thinks of you and even then not all of their opinions should matter unless you find them attractive or like them emotionally. If a girl I found attractive said I was ugly then it would hurt.