Consider a group of players in a game of chance. If all conditions are equal, the long-term results will be randomly distributed, with some big winners, and some big losers.
Change the conditions so that some players have an advantage, and eventually those players will be the only winners. How long this takes depends on the size of the advantage.
This is the basis of the mutation and natural selection portion of evolution theory.
For a generation after World War II, the US had a huge advantage: capital, undamaged manufacturing capacity, cheap energy, and most of the scientists and engineers. Thus, we 'won' the economic game, and it was attributed to Americans being 'better'.
We failed to notice that many other nations were catching up in education and technology. That the government and industry chose to dis-invest in research in the 1980's just accelerated the process.
As the playing field is now level (or even tipped against us), we should carefully consider how to gain back that advantage. We have done so before in the short term: arming in World War II, the Manhattan Project, the Space Race.
Do we have the will to do this when not faced with war, but with long-term economic decline?