because mathematics only really starts at proof writing
because it makes your grasp of “every” and “there exists” soo much more exact, its like you never really had it to begin with (and why that makes any difference at all)
because mathematics is quite possibly the most-suited subject for self-study
because the literature is really high-quality and perfectly suited to it
because “I am not a math person” is always a matter of never having fully grokked one or more specific subjects on the way (mathematics has zero tolerance on that)
but most-to-everybody have those holes, that’s completely normal. You don’t even have to worry about forgetting any. Mathematics will remind you. By mercilessly supposing them later (but patiently waiting while you go brush up)
because the lack of arbitrary deadlines allows for stopping and smelling the flowers
which makes not doing so seem like one of the great tragedies of institution-based math education
because it makes your comfortability in facing a problem completely independent of the scale of the problem (!) (“hard” just sort of suddently seizes to be a factor)
because writing a proof, any proof, feels like creating something that can stand forever
proof writing makes you suddently - after all those years! - reeaally appreciate the rigid and simple definitions in mathematics
when writing proofs you become intimately familiar with the various specific definitions of mathematical objects. Memorizing definitions is a side-effect of having worked together closely on something (you and the definitions)
it is extremely well-suited for life-long pursuit, feels like the perfect long-term hobby