Mostly because of the foreigners, and the small portion of Americans that are pro-intellectual.

EU also has a lot of immigrants as well, and also an even bigger culture of education and intellectualism. Why then don't they have more successful tech companies?

I think you're omitting the giant impact of the FED, wall street, power of the USD world reserve currency and the VC investor incentives of risking billions on ideas that may or may not be profitable, with the low risk for investors if their investments don't pan out.

All stuff that doesn't exist outside the US.

It's all downstream of the US's incredible geopolitical luck after World War 2.

The latest Gallup polling suggests anti-vax sentiment is at an all-time high. In no other comparable country on earth do 45% of people say vaccines shouldn't be mandatory. And it's not the foreigners on visas who are contributing to anti-vax sentiment.