Ask HN: What's the one thing you've always wanted to learn?

I've always wanted to understand Wiles proof for Fermat's Last Theorem. I have started on it but I have no good idea on how to approach the subject. Experts say that it takes decades of studying for a layman to understand it.

Web security because I'm a web developer who definitely builds unsecure applications. Unfortunately (and incorrectly, IMO) the full stack dev market doesn't really value security too much as it pertains to marketable job skills. For instance, I spend my time improving my Javascript skillset which has a greater impact on my bottom line at the moment.

Threads. I can't find any example that shows you how to do more than printf in a thread.

I want to learn an instrument. I'm afraid it's too late. I also want to learn all the latest deep learning stuff. I'm learning, but the progress is slow.

How to dance well. Would love to take a hip hop dance class or something. I think my fear of embarrassment keeps me from doing it.

(Shotokan) Karate. Practiced it for some years but stopped at some point because I was not able to match my ambitions.

Want to learn Virtual Reality. Not get time But I really want to do. Please if someone has good resource please post

Plaster walls like a pro. I tried to learn it but I haven't got the knack.

Ethical Hacking. Lack of time

Clay target shooting - not a lot of facilities on the south side of chicago

French. I have no patience for such an endeavour.

I have always wanted to learn how to sketch.

Public speaking.

Archery. Lack of time/motivation.