Absolutely correct. The brain drain for a small fraction of a percent that get visas to work in other countries is insignificant in the grand scheme of things. It's a mere trickle compared to the reservoir of people behind it.

Though, its more of a next generation thing that will be interesting - the changing demographics. The US has birthright citizenship - all the children born in the US to visa holders will be US citizens. That will do some interesting things in a few places when they start needing to pay taxes in the US if they are overseas and haven't given up their citizenships (n.b. I'm not an expat and so am not completely versed in the associated tax law).

Sending workers abroad and having them send money home to family outsources the social support structures needed in India and reduces the pressure for unemployment. This feeds into the growing nationalism and xenophobia in many western countries. In other countries it allows people with fewer scruples to take advantage of this labor force and essentially turn them into slaves (confiscation of passports and financial trickery).

I'm not sure where this is going to come back and where the ultimate costs with this policy are going to be paid - but they're going to be paid somewhere.

The Indian tech industry is certainly going for a synergy approach with western markets rather than... say, Japan ( https://en.wikipedia.org/wiki/Galápagos_syndrome ) or China (copy and maintain behind the Great Firewall).

Its going to be interesting to see how this all plays out over the years to come.