This is so much true! Indeed you can find absolutely everywhere absolutely incredible brilliant people in any area you want. The reason for the 1st and 3rd world is that is difficult to come by enough people and then coordinate them: is about critical mass and alignment.

About 2. also 100% true: intelligence/knowledge is totally independent of any other trait.

Right-- talent isn't that useful in a vacuum. You need economic and legal infrastructure that talented people can plug into to be productive. That infrastructure (a) takes a very long time to build and (b) depends on cultural norms that take a long time to evolve and don't find fertile ground everywhere.