Let’s be real, do you really need anything more than that? 
Plus, if you make $100k per month and live like this, you’ve probably got $98500 left at the end of the month. You don’t need to have too many months like that before you don’t need to work anymore.

This. The goal is to never have to do this shit ever again.

I have a colleague that just left the industry to become a violin luthier. Motherfucker doesn’t even know how to play yet. That’s how far they want to get from anything related to their work life.

Not sure you need to know how to play them, to sell them. Heck I had a bow re-stringing apprenticeship under a guy named Howard Needham. He can repair any damage done to any violin. He doesn’t play a lick. He ensures that at least one of his apprentices can properly play a scale to test the instruments. Or he used to anyway. Haven’t talked to him in a couple decades, so he may not be with us anymore as he was in his late 60s back in '99-'00
Yes, that’s what my colleague told me. They did specify that the luthier school requires that they can play a little, but not much.
Once you learn, your fingers never forget. I haven’t had a lesson in almost 3 decades at this point. I pick mine up and practice once a month or so, but I can still just whip out songs at the drop of a hat. Unfortunately I never learned to sight read, and only play by ear. I can “read” music, slowly. I just can’t read it at tempo.
A chair will be good for your back in the long run.