The idea that authors, artists and other creatives will keep pumping original work as part-time love affairs so that AI bros can grab it and mint a dime is... strange.
There'd be less art and probably lower quality art however to think people would outright stop making art due to any reason is strange (to use your words).
I make a painting. I display it. My neighbor sees the painting, studies it for a while, goes home, and makes a painting based on what he learned from mine. People still enjoy my painting, still credit me with making it, and if they like it might still pay for a copy. My neighbor, having devised a way to make paintings really quickly, sells paintings for cheap. Can I send him a bill because he's making money based on something he learned from me?
Granted, a lot of this boils down to whether AI learns or copys/remixes; if it only creates what copyright law would consider derivative works, then that's another matter.
I mean, it certainly isn't learning in the same way humans learn. Human learning involves some degree of understanding, which is wholly absent in AIs. There is, to my mind, no good reason to treat them the same because of this difference.
The entire software industry is built on open source software written for free by other software devs
In analogy, if creative production was to be paid by a benevolent patron that doesn't care if the work is then released in the public domain the economic equation changes. But this mode is not how things work at present.