Lets put it this way. If "Big Tech" relocated 50,000 jobs into swing states it would be the end of the Trumpist Republican party. And it wouldn't cost billions of dollars, it would save billions of dollars.
If Apple, Google and such weren't near-monopolies that can afford to burn billion dollar bills they might well be forced to move their operations to somewhere cost competitive.
But then their taxes would go up. They are happy to give to both political parties, but they ultimately don't want to pay much of anything to support any kind of social progress.
If you really believe the story that there is something uniquely productive about SV then it is really the land and community that are valuable and that community would be justified in raising taxes drastically until “Big Tech” started to move away.
If Apple, Google and such weren't near-monopolies that can afford to burn billion dollar bills they might well be forced to move their operations to somewhere cost competitive.