There was a snippet of a Reuters article on Gina Smith's blog today that made me think. The basic gist of the article is they did some experiments and determined most humans take from the rich and give to those less fortunate. I suppose that's why people like taxing the rich.
Meanwhile, I remember something from my college days that kind of illustrates this point. A bunch of us were playing Illuminati: New World Order (referred to hereafter as INWO). There was four or five of us as I recall. We were sitting around in the computer lab most of us worked at after hours. The game had went well into the night and we basically called it off. Here's why: the moment anyone got more power than the others, everyone else ganged up on that person. We basically fought to achieve some kind of equilibrium.
While we weren't robbing each other per-se, we were certainly making sure nobody had the upper hand.