China suffered very similar levels of brain drain... not even just to the US and Europe but also Singapore, Taiwan, Japan, and HK. It's just that the CCP has done a brilliant job modernising what was left of China from the utter ruins of the civil war/s and revolution from the 20th century. As the nation was recovering from the chaotic cultural revolution and its aftermath, the CCP managed to educate and provide for a great deal of the "proletariat" masses and made them productive (after tumultuous cultural revolution disruptions and blunders) then reformed further and further into actually becoming competitive and even more productive. The goal even for the late 20th century wasn't to have teachers forever farming. The first few steps of that journey was difficult and fraught with suffering but it appears that it was indeed worthwhile in order to transform China... a nation of over a billion uneducated farmers with the few elite families all doing absolutely nothing to truly modernise. Would the KMT performed better? Who knows. That's not a question to entertain anymore.
You can say it could be because the Chinese "peasant" class are just that much better or rather more suited to industrialising faster than the Indian equivalents. But honestly I believe it was all down to CCP stamping out backwards thinking, superstitious institutional thought, unifying the workforces and dictating paths through authoritarian micromanagement. It was just done pretty well. It's not perfect and definitely wasn't but it's a hell of a lot better than the utter chaos and total poverty that was and still is India. One uses technology to recycle and process waste while the other burns it so its masses can stay warm. Chinese attitude all over. The correct path may not always be kind at every step but sometimes bitter medicine is required and justified for the ends. The angry asshats of the world are just pissed that China came out of the stinking shit in one piece and all much better for it. It would otherwise have been a mess of a nation with rampant wars and fighting between regions and political groups, probably in a much worse state than parts of the middle east have been kept in since the Arab Spring. The ultimate wetdream of the western sadists, supremacists, western "liberals", and those who want to reduce their competition in the world while enslaving it under the Washington consensus, backed by dollar power and military power.
India cannot become a fast tracked economic wonder until it identifies its true obstacles and utilises some method for organisation (for China it was "good" authoritarian governance) that is suited for India's particular conditions. Relying on end-stage capitalism to turn things around is like trying to rescue a drowning man by taking him deeper into the water. The world will not allow humans to continue the capitalist method for lifting the rest of the world out of poverty. We'll have much higher toxin levels all around and inside us while parts of Europe turn into the Sahara before all of that happens. India should honestly consider a population limit before it's too late not just for them but the rest of the world.