That would only be the case if there was zero friction and cost to sponsoring a visa and everyone in the world was willing to move to the Bay Area. Neither of t

That would only be the case if there was zero friction and cost to sponsoring a visa and everyone in the world was willing to move to the Bay Area. Neither of those are true - just think about restrictions on H1B visas such as minimum salary levels and a limited total number. And think about how much more money someone would have to offer you before you'd consider moving to the other side of the world where you don't know anybody.