I completely agree with you. but then, I'm not from the usa and I have experienced the wonders of good social systems in Germany and in the UK.
As you put it, if there was some kind of "richness cap" (say, 1 billion) and all the rest was held as interest generator for social services and society, population wouldn't have to depend on the "goodwill" of people, but would have the basic necessities fulfilled.
Humanity will get there at some point. There is no other alternative, given population growth. But right now we humans are still quite underdeveloped as a society.