I think #4 is definitely right (though not necessarily the entire story). For my entire career, it has been necessary to either move to SF / the Bay (blech) to

I think #4 is definitely right (though not necessarily the entire story). For my entire career, it has been necessary to either move to SF / the Bay (blech) to work for most of the world class tech companies, or work for one sprawling enough to have lots of satellite offices (mainly Google and Microsoft). Now I'm seeing opportunities at all kinds of great companies that I can actually apply for. This started before the pandemic actually (I date it to Stripe's "remote headquarters") but has really picked up. Nowadays if I click through to the careers page of a company I admire and might want to work for, I'm surprised if they don't have a few remote positions. Only a few years ago, what always happened in the situation was "local only, based in the Bay" -> close tab.