I was talking about academia, which is why I said "scientific research."

What SV is doing is perpetuating US dominance in software (and some hardware development fields). If most of the skilled software engineers in the world become off-limits to SV companies, then the global software industry will cease to be so heavily concentrated in SV.

It's strange and amusing to see people earning hundreds of thousands of dollars a year complaining about foreigners undercutting their salaries. They imagine that if immigration is restricted, then the open jobs will go to Americans. The reality is that the jobs will leave. Aesop must have written a fable about this sort of situation.

Do you think Xi and Modi would be allowing their citizens to work and study in the U.S. if it were not advantageous to China and India?

It's possible for both the US and China/India to benefit. The US gets a massive yearly influx of extremely smart students, many (maybe most) of whom want to remain in the US. Even if they do eventually return, they work for US research labs while they're getting their degrees. China and India eventually get some of the students back, now with increased skills.

But it's not as if China and India are in control of this process. Unless they're going to take the drastic step of preventing young people from leaving, it's not up to them to say how many students go to the US. They do increasingly try to get students to return, and any increase in xenophobia or restrictions on immigration in the US will make that easier.