> There would be no A bomb without this, for example, nor US moon missions. These were mostly German weapons scientists brought to the US near the end of WWII. The alternative was being sent to Russia. Russia was brutal to PoW's so given the chance everybody tried to surrender to US and European troops. Not really regular brain drain that time.

Brain drain always happens from poor to rich countries. Those able to move to greener pastures will, I don't blame them. This is even happening within the US in Illinois. High taxes and precarious government have led to massive migration away from the state. Highest percent of college students going out of state, and average person moving to Illinois makes nearly $25,000 less than average person leaving.

You can't blame people from wanting a better life for their family. In the end it does concentrate wealth, but maybe it will eventually just concentrate the population? This seems to be happening in China, with massive migration to megacities. Rich or poor, the countryside is being abandoned, so there's not many being hurt by the migration, just empty buildings