Your comment sounds like you didn't quite understood the point I made.
The whole point was that US benefited greatly from WW2 to reach the position of world's hegemon. But that happened nearly a century ago, and reaching the position vs maintaining the position are two entirely different sets of challenges.
My point was that WW2 gave the US a running start, but it still required work to preserve that advantage. The US's postwar investment in higher education and R&D was the key competitive advantage that allowed the US to preserve it's dominance until the present day.
To put it another way, WW2 helped attract the world's finest research talent, but the technological and scientific achievements that followed were the result of the investment in domestic talent that followed. You cannot have the likes of silicon valley without the US's postwar investment in higher education and R&D.