Imagine a rich friend inviting all his middle-class mates to a party. He has good family, is well-connected, very educated, has a beautiful hot girlfriend. Lots of money. Of course, the have-not's are going to resent his success at what they call "unearned privileges." Now if another guy shows up at the party who used to be one of these plebs, but is secretly backed by rich friends. He looks and talks just like the plebs do. So obviously he will be more popular.
That is why in older times, people used to only mix according to their social class. The gentry would only hang out with their fellow landowners.