> I dont know of a single person here on a visa making less than 150k salary

Don't have data on this but anecdotally the base salary range for most YC startup jobs advertised here is around 150k-200k based on what I see.

You are right that it does amortize if the employee stays long enough.

> it does amortize if the employee stays long enough.

And I expect workers on H-1B change jobs much less frequently than citizens & green card holders (and holders of "safer" visas), since changing jobs on an H-1B involves more risk that can end up with you being required to leave the US.