If it doesn't come from somewhere, it doesn't exist.
When you write that it doesn't have to come from somewhere, you are just arguing that costs (time/money) will be born by the musicians themselves. Basically a donation to society.
Your conflating money with the thing it pays for. They are not equivalent.
I make all sorts of cool art for free. No money, comes from nowhere, sometimes I pay for materials or prints. The printers aren't the creative ones (if they dare I'll take my work somewhere else next time). Then I give them away (because birthday presents are hard).
And sometimes I make music but you can't give that to people, which very neatly describes the whole problem in a microcosm: You can give someone a performance but that's ephemeral, a one time thing (and only if I were good enough that'd be passable birthday present and even if I were a rockstar, after a while you gotta ask yourself wtf you're doing and why). You can give someone a recording but that's worthless because it's just information which has near zero value--and IMHO it's completely ridiculous to expect people to pretend otherwise (unless that's the art but then it's not music and let's not get into the art of pranksterism right now).
The other option is they stop making music--haha! Seriously, who is going to make them stop?? Some wise people once said it takes a nation of millions to hold them back (maybe they meant something else, but they also meant this). Another wise person once said that we are nothing but the sum of our parts and that which we give away for free.
So there's music that is not going to be made if you don't INSERT COIN. Then there's music that builds from divine pressure (wise person said "can't touch this") and forces its way out no matter what. Cry me a river if we lose the former, thanks to technology, it'll just create space and breathing room for the latter.
When you write that it doesn't have to come from somewhere, you are just arguing that costs (time/money) will be born by the musicians themselves. Basically a donation to society.
The other option being they stop making music.