Probably because you need to be some form of elite to make it in American politics.

Sure, there’s underdogs and outliers… but for the most part if you want to have a substantial effect on American government you have to kiss the ring. Which means becoming part of the in-crowd, or the “elite”. You can promote social justice, and certain economic reforms, generally when you have a blue name instead of a red one… but you still have to obey the golden rule of politics… don’t make waves that the majority of politicians aren’t already riding.

It sucks… and if people get off their ass and actually participate in democracy, it can change… but until then this is the standard.