Hilbert space

>Are those mathematical consepts or quantum mechanical

that's like saying is the sky blue or azure

>professors fail 90~95% of the class just because they can
Maybe that's why those countries aren't developed. Academic rigor, challenging subjects, and gaining a real understanding of disciplines is great, but it sounds like your professors are on a power trip because they lacked any power when they were young, so they take out their frustrations on students.
By the way, the vast majority of the world's population, including people in developed countries, have never even heard most of those terms let alone understand them.

>vector calculus

only thing I loved in Math

>He didn't take vector calculus in elementary school
You never stood a chance

Actually I really love all topics with vectors but practically nothing else in math. I haven't gotten to vector calculus yet though, I'm kind of excited

Literally the most aesthetic notation in mathematics.