You are, of course, free to believe as you wish.
However, I see no empirical evidence to support your belief.
Can stupidity be trained?
Intelligence and training are very different.
You can train flatworms. When you do that, do they become more intelligent?
I’ve been training doctors since I was trained myself. People of a number of different IQ levels can be successfully trained. But the further down the scale someone is, the harder they have to work and the more effort it is for them to retain information.
And it is not the case that the most intelligent ones make the best doctors. High IQ does not confer good character nor good work habits. Super-smart medical students can get away with things more ordinary ones can’t.
It is probably true that the IQ band for doctors is more like 110-140+, and that people in the 90-110 band are going to struggle.
But the evidence that you can “train” an IQ of 90 up to 110 by requiring Algebra II in high school is, well, nonexistent.