You can't teach any arbitrary thing (nor temperament) to any arbitrary person. For a specific example, consider: https://en.wikipedia.org/wiki/Teichm%C3%BCller_space

I can say that not only would I never get anywhere with math at that level, but some of the related mathematical pages on Wikipedia surpass my ability to even tell if they are real or the work of cranks.

For any random person, there are things they can't do or learn because of the way they're made, any more than a cow can do calculus.

What's deceptive is that people constantly tell you that you must believe in yourself. But the reason isn't that believing in yourself is sufficient for success - the reason is believing in yourself is necessary to succeed so everyone who is successful attributes their success to that.