When I hear about people doing something like a Rust project for fun outside of work I assume they either have zero social life or are very young.
To me it’s not weird to do some Rust programming out of work.
What is weird is if people believe it would be some sort of virtue.
If it’s fun for the person, great! If it’s not fun and you are not getting paid for it - maybe rather find something you like to do.
But even for those of us who are more established, I think it can be a good thing to dial back our social lives from time to time and invest in building and maintaining our career capital. That is especially true if you find work boring. It is totally fine to be bored at work for a time, but long term that is a sign of stagnation. Stagnation, in turn, can leave you in a vulnerable place when market conditions turn for the worse.
You can prioritise anything, if coding is fun for you you can find the time. (3 kids, 30s).
Same for exercise, and pretty much anything else