Meh, I think culture, economics systems, and political systems play a very large role in determining economic success. Who would have predicted in 1945, that 60 years later (in 2005), the world's #2 and #3 economies would be Japan and Germany (both just devastated by WWII)?

The people who settled and immigrated to America were not picked randomly. The vast majority of them moved consciously with the intention of building a better life. The sub-set of Europeans who moved to American is distinctly different from the sub-set of Europeans who stayed in Europe.