The stability of complex societies depend on a division of labor. This division of labor inevitably leads to economic differntiation and social stratification. Yet, what allows for the lower-status members of society to tolerate this position? Here is a short list of options;
1) Reward satisfaction on some other level: I might not be a billionare, but I find satisfaction from community, family, god, the Red Sox, good food, my dog and my garage hobby.
2) The illusion of upward mobility: The central American meme is that you can achieve anything with hard work and dedication. The role of government is to ensure that this remains plausible. Our american society will have difficulty standing with a permanent divergence in class.