This is quite ironic, considering that Mozart made most of his (relatively little) money by touring and composing for wealthy patrons. Somebody else made much more money out of him: sheet printers, who also ended up being the real force behind original legislation on copyright.
Plus ça change...
It's not ironic. He made his living (little as it might have been) by doing what he wanted to do. He wasn't cleaning toilets on the side to supplement his hobby of composing. Other people making more money off his work doesn't change anything. His passion supported him financially.
He wasn't relying on copyright laws, which is what the parent poster was implicitly talking up with his statement; i.e. a world without copyright laws did in fact produce a Mozart, and it will keep producing it regardless of legislation.
Exactly: gigs, concerts. This is how musicians make the bulk of their money when they are locked into shitty record deals. And it provides an experience people are more than happy to pay for. Free music drives concert ticket sales (ie. radio singles promote new touring bands).
The point is that it was possible for him to make enough money at his trade to move beyond the amateur stage. It's not clear that many people will be able to do this now, at least not those that can't cultivate a healthy live following for whatever reason.
Interestingly, Mozart got paid to write music for his patrons. Today, I don't see any bands being willing to write music for payment. Could I get Elton John to write a ballad for my S.O., for instance?
