I guess most everyone had a bad experience with a teacher at some point in their lives. Mine were the grade school teacher who whacked me on the hand with a ruler for using my fingers to count. High school had the teachers who gave more attention to the bright students. College was that young, liberal, elitist English teacher who talked down to everyone and made us read books that had nothing to do with anything.
I didn't particularly like school, and dropped out of HS in my last year. I got the GED in the Army, went to college for two years, then quit. I saw no future in being a music teacher, and was playing in a rock band at the time.
Then I went to a trade school, became a bricklayer for 12 years. While doing that, I went to a technical institute at nights, got an Associate's Degree, and became an electronics bench tech. The tech school became a legitimate University and I ended up working there for 15 years, until I reached burnout.