That's not really how it works. Immigrants also benefit from coming to the US.
Skilled labor immigration is great for everyone involved, and bad only for the countries that suffer the brain drain.
But it's not zero-sum. The damage to those countries from losing talent is smaller than the benefits to the immigrant, their new country, and ultimately all of humanity.
> and bad only for the countries that suffer the brain drain.
That's a pretty big qualifier!
> The damage to those countries from losing talent is smaller than the benefits to the immigrant, their new country, and ultimately all of humanity
Isn't it the opposite? Creating wealth and technology in India helps a billion quite poor people. Creating wealth in the U.S. helps 300 million already rich people.
>bad only for the countries that suffer the brain drain
Except those countries continue to decline and eventually become a global issue. India is on the cusp of a water crisis which is going to turn into a massive refugee crisis - how different would the situation and institutions be if the top 10% of the population hadn't been siphoned off?