One of the smartest people I know never made it past the 7th grade. Back in the 70's he was building robots that were remote controlled. They were incredibly cool- they had hoses with different color fluids going through them. He made a fortune taking them to trade shows and putting them through their paces.
My former brother in law, I have no doubt, is a genius... He went to the 6th grade (but didn't finish). If I was wealthy I would set him up in a machine shop and turn him loose. One thing he invented was a tool for going inside automobile engines to repair them without taking them all the way apart (kind of like arthroscopic surgery for cars) it had a light and pincers for holding tools or picking up parts and it was magnetized so it would pick things up. That's just one of his inventions.
I never went to school until I was in my 40's when I went to adult ed. I got into college on the strength of several stories I had written. I had a similar experience with teachers myself! My oldest son's teacher diagnosed him with ADHD and said he couldn't come back to school unless I drugged him. I questioned her medical credentials suggesting she might ought to leave diagnoses of this sort for qualified medical personnel. She said I was agitated and threatened to call security... I pulled all four kids out of school and taught them at home. When my wife and I split, she sent them back to public school... every last one of those kids were the smartest in class!