fields currently that would still be at the top of their fields if every single person on the earth was groomed for their position.

I mean look at the NBA. Top 4 players are international. That was unfathomable 30 years ago. And that is with a fraction of the world having access to basketball/coaching/etc (and basketball has the huge advantage of being able to see talent (or size anyway)...for most professions that isn't possible).