I agree that some significant portion of modern US wealth is a product of the post-WW2 world empire (and the dollar reserve as a form of tribute).

However, USA (and Argentina) were dramatically rich in the late 1800s due to free market policies that brought about a much higher degree of economic activity than in most of Europe.

The US is now a mix of industries that have been made into fascist cartels as well as those that are relatively free. Some of the present wealth is due to actual economic productivity even in industries laboring under government intervention (eg the US is the world's #1 food exporter)