The tech industry tends to fixate on the cutting edge. Global Foundries has process tech that is 10 years out of date (14nm). 14nm is fine, a lot of good chips were produced 10 years ago. If we optimistically assume that there are usually a few players in the market that are 10 years behind, that means many sellers will be at 3nm soon.

TSMC is dominant, and we could imagine that in a wartime scenario maybe that'd matter (big maybe, why would a military need mass production of chips that didn't exist a few years ago?). But for anything else, capitalism will happen and 60% market share is impressive but not concerning. The current strategy of trying to restrict China's access to chips might easily spur some competition.

> I'm wondering if there has been any time in history when so much of our critical technology in our world has been concentrated in so few producers.

Nuclear bombs? And I'd assume this happens all the time. Any cutting edge market, in fact, seems like it should often start with one big player that has a better understanding of new research that is then slowly worn down by competition as the knowledge spreads.