A day job doesn't have to be your side project's enemy. If you do web dev at work you get paid to do something that makes you efficient at web dev. Then you go home and work on your side project and you don't need to spend hours struggling with webpack or why str=((num || fallback) + '') works, so your side project is done more productively too.
Come home at ~6pm, make/have dinner ~7pm, exercise ~8pm, get home and shower ~9pm. At this point there's not much time to do work, especially if you have to go grocery shopping, do laundry, clean, have a family, or any number of other misc things like get a haircut or have clothes dry cleaned.
It's so funny to read stuff like this from people who don't have kids. I remember thinking the same. Now I look back and realize with horror how friggin much free time there was and how much more I could have done with it!
A side project can be 2 hours a week. You can optimise making dinner so it take less time (cook in bulk, make some meals salads). Exercise can be done at home, probably 30 minutes in the morning and evening is more than enough.
As with everything else, you have to prioritize - there will never be time for everything. Meal prep and home exercise alone can cut that schedule down to 60-90 minutes, so you can begin on the side project at 7.30 pm.
7.30-9.30 would give you 2 a day. Say 2 nights and then on the weekends. 8 hours a week. That isn't much but the trick is to do something quite focused.
I personally just get so drained after a day of work, on top of exercising, and some sort of recreational activity would be nice. The work isn't hard. It's the thinking that goes around the work that is the draining part. Especially if you want to keep a job. Others can perhaps compartmentalize a bit better than I can.
Working on greenfield projects is so much less mentally draining than working on some old thing with only 10% of its functionality encoded in tribal knowledge that interacts with like a 100 different services that you need to constantly be learning about.
Definitely. Greenfield is rare in my experience though. And there is greenfield solo (awesome) and greenfield team of 20 all chucking code in (instant legacy!)