I think it's easier to go from nothing to absurdly successful in the US than almost anywhere else. It's probably harder to go from nothing to the middle class in the US than it is in Europe or other developed countries. It's also getting harder to remain in the middle class in the US than in e.g. Germany. It may be easier to go from middle class to 300-500k/yr in the US than in most other places, too (still difficult, but easier here).
The big area where the US is failing people is at the low end. Multi-generational poverty, as well as people who had 1-2 generations of moderate success dropping back to poverty.
The big area where the US is failing people is at the low end. Multi-generational poverty, as well as people who had 1-2 generations of moderate success dropping back to poverty.