Because the majority of US citizens of school age are from historically disadvantaged minorities and you're saying they're just not good enough to compete with the East Asian global majority even with better education. In fact, you appear to be saying we shouldn't even bother to try and that people from wherever it is exactly you're from are innately superior. That's why it's racist and offensive.
There are almost 8 billion people in the world and 320 million in the US. Of course most talent is foreign. No one who wants green cards for engineers is arguing for a decrease in education funding
