Sooo, in my 5 years of high school, I had 5 different IT teachers...
Now, in Italy Highschool goes from 14 to 19 years old, I started programming some days after becoming 13, and "programming" classes begin on the third year, so I had quite a headstart on my classmates...

Now, for the third year, I had an awesome teacher, he noticed I was ahead and... Bored, so he gave me some extra stuff to study, he's the only teacher I've learnt anything from, it was awesome, very stingy with grades, but getting a perfect score with him was so satisfying.

Fourth year, the new guy was old, very old, at least 70, his lessons were just him talking about how programming was when he was young.

But then... During the second half of the fourth year I changed class due to bullying under a teacher's advice, and HE happened...

My new IT teacher, one of the most ignorant, awful people I ever met...
He's literally the reason I only went back to that school once, because another teacher needed help with a course...
One day I made the HUGE mistake to say that his "while(i <10000000000000);" wasn't very efficient for making a delay, because it didn't free the CPU, and since then:
- I never got more than 7 out of 10 at his tests
- He insulted me in front of the whole class
- He sabotaged the oral part of my final exam, shouting that he hated D'Annunzio when he saw he was in the literature part of my thesis (needed him to connect to WW2, and the Memex, that then allowed me to start talking about PCs and programming, my thesis was about the influence of lisp on modern programming languages), loudly chatting with other teachers when I was trying to keep calm (a teacher who knows me quite well, and was there to see my "performance" thought I was going to snap at some point), distracting the english teacher when I was exposing the english part of my thesis and pressuring the commission to give me 99 instead of 100 out of 100

So yeah, he almost made me hate the only thing I'm good at, undervaluing my work and my skills, undervaluing and humiliating me as a person, and I think that if I meet him again I might spit on his face...

So yeah, my biggest "programmer enemy" was a person that then did everything in his power to make my last year and a half of highschool hell

Now I can gladly say that with the help of my tutoring, some of my university colleagues are starting to appreciate programming, and my engineer friends ask for my help when they need advices about their code, and it's giving me motivation to keep doing it and becoming a better programmer to keep up with their expectations