How do we determine that limit ?
Most Americans ( middle class and above ) are richer than most people in the world.
Way richer than most people in Africa or poorer parts of Asia can ever aspire to be.
Consider that when competing for resources these poor people are competing with wealthy middle class Americans.
Add to that the USD being world's reserve currency makes life easy for a small part of global population earning in the USA and makes it harder for people in every other country whose currency might not be competitive compared to the USD.