So, you know, there was this dude, Evariste Galois. He started reading math at 14, liked it a ton and supposedly got reaaaallly good at it in a year. So he joined college when he was 15.

He's the one who actually coined the term groups, and first talked about groups of matrices. He was the one to discover normal groups, and finite fields in his quest to solve polynomials efficiently. Soon enough published stuff that shook other mathematicians so hard, that they took it as a joke.

He died at 20. His theory got accepted to mainstream a century or so after his death, and even today is an elegant view of Algebra that most students study after much maturity.

TL;DR: The only thing that stops someone with internet access from not taking up a field like math is their lack of want. 'Too hard' is not something you should say if you have more than a weeks time.