And then even more specifically - at least in terms of local problems - that pushes up the value of compensation for a lot of people in the SF Bay Area which inflates the cost of land there.

Staying out of whether or not the concentration is a problem at the national/international level, is there any realistic alternative short of massive protectionism a la China to force home-grown tech companies in other parts of the world?

Ths stock market is not considered in GDP. So by that measure it does not directly impact "economic growth." I can see an indirect relation that says that US investors (primarily through pensions and 401Ks) are the primary benefactors of a growing US stock market which then translates to more investment and opportunity of US citizens, but that is a pretty long trail to account for our economic path right now.

The claim here is that the tech innovation is occurring in the US. It adds value globally, but most of the profits from that value are being realized in the US b/c the innovation is by US companies.

There’s no natural law that says technical innovation must occur in NA, but due to contingent historical conditions, it is occurring here. Thus, the gains are being realized in the US stock market b/c it’s the one capitalizing the winners.

They’re generalising to say the world uses Apple, Google, Microsoft, Zoom, Cisco, Tesla, and so on… US tech stocks. We use them and they gain revenue and profit.

Of course there are many successful tech co’s outside the US but (and I haven’t looked) I imagine the US tech stocks must overshadow every other countries tech sector.

US cultural dominance for one thing, then success begets success - lots of VC money in the US because the US is rich which gets invested which returns even more and makes it richer.

US businesses more likely to work with US suppliers, US customers more likely to buy from US businesses, then those dominant domestic positions can be used to expand globally far easier than say a Spanish firm can expand into the US.