Sure, but the vast majority of the wealth of building SpaceX and Google doesn't go to me. It goes to people like Musk and Larry Page.
Also, a lot of the wealth from the tech industry does spill over to the larger community. You're strictly better off having it. If the US had just stuck with their 1970s economy on the theory that any new industries wouldn't distribute their benefits equally, it would be vastly smaller, less powerful and less wealthy. Surely that's obvious?
Of course your country is better off if you have successful companies and high-income jobs.
Intelligence is not equally distributed. The vast majority of human populations have close to no talents. Your best bets are Euros, East Asians, and upper caste Greater Indians. That means we shouldn't compare 300+ million with 8 billion, but the majority of talent is still clearly born outside the US.
Just a clarification -- you probably agree.
That said, I think you underestimate many places. For example, Iran is one of the most ancient civilizations out there, and the Persian diaspora in the US is pretty productive, even though the country proper is a retrograde tyranny with very bad economy.
If you can snatch them, they will build SpaceX or Google for you. If not, well, they will do so either elsewhere, or not at all. (South Africa does not seem to be a good place to start business, and neither is Russia.)
Can you gain prosperity by employing three mediocre people instead of one talented one? Maybe, but you won't get a new vibrant sector like Silicon Valley this way.
Europe, where I live, is a lot more gung-ho on mediocrity and forced equality, and we seem to be the ones with clearly stagnating living standards, not you.