The U.S. is where the money is. In canada between public and private sector about 30 billion dollars are spent on research and development. Across the entire EU, this figure is more like 440 billion dollars. In the U.S., the figure is 885 billion dollars.

https://www.conferenceboard.ca/hcp/publicrandd-aspx/

https://ec.europa.eu/eurostat/statistics-explained/index.php...

https://ncses.nsf.gov/pubs/nsb20246

My point was that in this alternate hypothetical world, there likely wouldn't be the large number of US domestic R&D companies to serve as valid targets for such investment, as many of the clever people who start them or staff them wouldn't live in the US. Those people would instead be starting and staffing those companies wherever they did live — or in whatever country they could immigrate to instead of the US, with that country then supplanting the US's role as a global R&D center. Which would put American investors in the same position that other countries' investors are in: having money, but few domestic R&D companies that aren't already plump with cash, while most opportunities are foreign.

(Or, if we really lean into the "alternate history" bit, then the US might not have so many rich investors to begin with, as those investors would have been the ones living in that other global R&D center country, who became ludicrously wealthy when their investments into the domestic R&D companies in that other country bore fruit.)