Tax revenue is just a percentage of the income you make.
Is your work/activity/service really worth anything, if noone is willing to pay for it?
Nobody pays for my girlfriend to show affection to me, or spend time with me. Nobody pays... you get the point.
So many of the best things in my experience have not been quantifiable, or in fact even actively hostile to commerce. That guitar player was not getting paid, but he wanted to play because he liked the vibe of the bar. For all I know he was good enough that he usually gets played. I know that some of the top performers in my country (stadium-level audiences) would do so at no cost at this bar, randomly, and if you were lucky it was when you went there for a beer.
I do hope you don't really see the world as a matter of finances and payment. It's depressingly reductive.
You can still do all that, but you're expecting other people to do paid work, the government to take away a huge chunk of that money, and then give it to you, so you don't have to do paid work, and call your mom.
You can still play your guitar (or do whatever) for free, just for the love of doing that. But if you didn't get people to give you money (food, services,...) for your music then, or for you calling your mom, etc., you cannot expect the government to force them to do it on regular basis, if you play/call, or even if you don't.
All the things GP listed were things that enabled him to make money and buy all the things, yet no one got paid for it.
people pay for sex, yet sex workers aren't legally able to report their income and pay taxes.
I challenge your assumption that someone's worth to society can be accounted for by tax revenue.