Yes. It's the same with all of the engineers I know (and I suspect it's the same with all professions).
With my engineering friends, we had to set a rule that if we're at a social function that includes people not in our field, "talking shop" is expressly forbidden. This is to prevent a problem that had gotten out of control -- having a handful of people talking about arcane things that nobody else can understand, let alone are interested in.
Agreed. I spend a lot of free time reading about and discussing technology. Occasionally teach, occasionally do some advising.
But I rarely have a side project which consumes my time. I guess the equivalent would be a nurse going and taking a shift at another hospital.
You're looking at the wrong profession. A nurse can't "just" go and start nursing stuff. Programmers are like carpenters - they can just go and start building stuff for themselves, using the same tools and skills they use at work. Except they also have an industry-imposed, medicine-style continued learning requirement due to how fast the field keeps changing.
I think in most fields the top performers are going to be investing significant effort outside work to practice, learn, and improve themselves throughout their career. Coding is a little bit unique compared to certain professions because it can be done alone and without incurring much additional cost.