There are countless takes on this, but I'll add one more: Silicon Valley's failure is in being unable to diversify effectively from a failure in city-building. For a good stretch, the bay area was the place to be. Lots of people wanted to be there, whether or not they were engineers. The cost of living made these ambitions completely unreasonable, except for the well compensated engineers. Monoculturalism is a failur…
I think a big challenge here is single family housing with a yard is by far the most desirable housing in the US. I doubt folks would accept a significantly more dense living if they were the engineers of tomorrow. They’d expect the single family home and yard for their work. Where in the USA is this not a challenge? Single family zoning is everywhere and existing residents in most American cities have little reason…
Simply put, the fact that prices go up in densest parts of SF and NYC basically confirms that there's people that enough people want real cities to bootstrap the process.