You realize there's also a lot of racism and xenophobia that plays into this too, yeah?

It's easier for some to care less about people that don't have the same accent or clothes or common background.

And the US has a lot of financial liquidity.

Hence, you'll get a lot of people starting companies in the US while the ICs are remote - also where many of the buyers are likely to be of your product.

Top talent in low cost areas are not significantly cheaper than in high cost areas, but they offer far greater risk. Most companies want to keep the core product work, where they're competing hard, near themselves.