This is conflating businesses that solve billion dollar problems with people who individually contribute so much to a business that they solved the billion dollar problem all on their own. The latter is probably possible, but it's not necessarily the case that all billionaires and up today were such individuals.

It might be that if personal wealth alone were (effectively, by taxation) capped to $100m, we would still have exactly as much collective wealth, innovation, and value creation as we do today. Possibly more, because of more wealth distributed onto shared infrastructure and into the fluid economy.