This assumes that the number of jobs in the US is magically fixed.

The thing is that all these mega-corporations have offices across the world, but currently want to hire in the US. You and I want our personal jobs to be expensive, but we don't want the prospect of hiring us where we live to be too expensive. And even aside from cost, you also don't want them to say "there's not enough employees there, it's not worth hiring."[0]

[0] I'm technically no longer living in the US, but I was until recently.