I used to think that inequality explained everything, but perhaps I've grown up a bit and now I think it just explains most things. I attended a lecture by Robert Sapolsky some years ago and he was quite big on studying stress responses in primates. One thing he said that stuck with me was that in highly unequal primate societies, they measured higher cortisol levels amongst all members; even those at the top. Certainly it seems that the pathologies of American society have only intensified along with wealth inequality, but obviously teasing out cause and effect is fiendishly difficult at such scale.