If you waited until the day when Americans have to go to China for an education, then the US is longer in a position to deal with the problem as effectively as when it just started losing foreign-born scientists.
The US was built by immigrants. That is the root of its power, a gathering place for talents all over the world. If you still question whether it is of any concern for immigrants, especially high-skilled ones, to feel unwelcomed here, then I afraid I have no arguments that can sway you.
it is a competition, so it doesn't matter if it was china getting better, or the US becoming worse. The end result is the same.
To your point, yes US residents send their kids abroad. From a total of 15k in 2000, up to 34k right before the pandemic.
https://opendoorsdata.org/data/us-study-abroad/all-destinati...
It is true that US immigration is horrible, but that goes for may other countries as well. I don't know what the cause is or whether it is something that you should even want to repair.