Uh, this is the first time I have heard that Americans are somehow genetically or racially superior thanks to their national founding myth. Certainly sounds like a similar theory to a certain other, now hugely discredited political outlook I won't mention.
It seems to lack explanatory power - why are there so many other countries composed of the descendents of migrants that are not as wealthy? Why are there countries composed mostly of lumpen aboriginals and left-behinds that are even wealthier per-capita?