Some pretty people are mean because they can get away with it and never learned that it's often counterproductive in the long term.
This is just some people, others act differently.
I don't think it would be evenly distributed, but it goes something like that. You can choose to behave confidently up to a point, but people reject such behavior from an ugly person. Ignoring this social feedback can get you into a lot of trouble.
>I've always found the physically-unattractive-but-socially-attractive especially interesting because they've succeeded, often along with a very cool peer group.
Some of these are brutal too. I've known some real busted dudes who got attractive girls to like or marry them somehow. I assume it's often money, connections, and/or encountering the right person who is a sucker for your particular characteristics. Imagine being the ugly brother or nephew of a solid 10 (guy or girl), or being a multi-millionaire. You'd easily get many times more opportunities in all areas of life.