At least people can overcome abuse and thrive off of it. I don't know a single person who had an extremely cushy childhood who is 'on fire' for anything or striving for greatness.

You need adversity to be great. Not all adversity is abuse. The American dream is about overcoming and flourishing to the limits of your will power, taxing people who have succeeded to provide succor to people who don't care about themselves is corrosive to the national spirit. Come visit some time, I'll show you around.