I think you can make that argument for my country of origin. They can add negative for the brain drain as far as I'm concerned. I guess the same holds for a lot of Indian or Chinese students who came to the US. As for grad school and postdocing, the way it works is that this has very little to do with training or investing. I feel I earned every cent they paid me for doing research.
Grad school and the postdoc system pretty much a cheap way for universities to get labor at 50-70% of the private market rates. Universities call grad students "students" so they can get around various labor laws and not paying for things like health insurance. The use postdocs because it's easier to lay off people compared to staff scientists.
So they hire persons with masters degrees to do grunt work for 25k/year and call them grad students. Then they hire the smart ones with PhDs for 40k/year and call them postdocs.
Basically you're put in front of a computer or in a lab and told to work on this task much like private industry except maybe your work is a bit more interesting(?) You write reports about your work called "papers" and after 4 years you write a giant progress report and call it a "PhD Dissertation". There's very little actual training or education involved in this process. Or at least not more than you find in the private sector.
It's pretty much labor like it is in private industry. I guarantee you that without grad students and postdocs, very few scientific papers would be published, because grads and postdocs are the ones doing the actual research.
When you see news of some professor discovering something, you can pretty much be sure that it was discovered at 11 in the evening by some grad student or postdoc of his. He was just the manager and subsequently in charge of public relations. That's fine BTW ... it's not like Steve Jobs single handedly built the iphone, but he still gets all the credit for it.
I myself published over 30 papers in my career, many of them first authored putting in 100 hours week a lot of the time, so I think I earned the money I made.
You can argue whether those papers are the equivalent of an $800 toilet seat, but that's a different discussion altogether. I put in the sweat equity "on the bench". I earned that money.
Professors mostly spend their time teaching, managing their workers, excuse me, "teaching" their grad students and postdocs, and writing grant proposals. Academia has the same typical structure as anywhere else. The only time you spend any meaningful effort being "educated" without giving back is as an undergraduate.