This is the question asked by John Cook on Twitter. He lists responses from different people:
- R
- Version control
- Linear algebra
- Advanced math
- Bayesian statistics
- Category theory
- Foreign languages
- How to not waste time
- Women
Mine are: quantum mechanics, Python, cooking, the language of philosophy.
What learning curve do you wish you'd climbed sooner? Give reasons and stories if you feel like it. Do you think other people should climb the same curves?
Playing the piano or guitar, even at a semi-beginner level, can be a lot of fun. You won't make money off of it, but you can show off to friends and family members. It's like playing tennis or basketball: you need a high level of skill to compete seriously, but you don't need to be even as good as the local high school team to have fun with your friends.
Incidentally, I think it might be easier to achieve minimal competence on a guitar than on many other instruments - you can perform a lot of songs just by learning a few chords and singing the melody.