You are not dumb
It is common among some teenagers from 15 to 17 or so. They call themselves “dumb”, “idiot” and such these words. They think they are not worthy. To be honest, I had similar behaviors when I was a teenager. And now I know I was wrong.
The reason I was considering myself an “idiot” was simply because my knowledge was very limited. And my learning process was super slow. But after years, I have come to this understanding that a slow but constant learning rate can have great effects after a few years. Actually, I believe a slow but long term and constant is much better than a super fast progress which sometimes comes and most of the time is absent. There is a proverb for this in Persian: The true traveller is the one who goes constantly slow rather than the one who doesn’t walk the way but sometimes does a quick run.
The problem’s that these teenagers believe they are idiots because they can’t become the Master of one thing(for example some branch of Math or some programming language or any branch of science) in just a 24/7 effort.
If you want to master something, you don’t need to move fast. You need to have constant and slow steps. You don’t need to push yourself too hard, just have small daily exercises and try to not miss a day. As a progammer, I tend to code or think about problems almost everyday. Even when I am with family, I sometimes think to the problems. Not just technical ones but also philosophical ones.
If you want to master something, and you are a teenager around 15 or so now, it is a good time to start. But don’t expect to understand everything instantly. It is a fact that some concepts in science, need some effort and time to deeply understand them. And usually you can’t do it in half the time, your mind really needs to adapt itself to the new situation.
A real world example
A friend of mine, Behnam Simjoo, is TA of a fundemental CS course in Hormozgan University. He and I been doing programming(and not Computer Science) for long since school. He always says those without programming background can’t have their mind adapted in just one semester(3-4 months) to think like a programmer. And the University is quite on the wrong track in asking them to pass this course in one semester. Needless to say that the way a considerable number of students in this country, perhaps a majority of them, are not even near the right track in choosing their academic branch which is mandatory from highschool.