They are not appropriating anything, they are remixing and creating derivative works, something that people have done since the dawn of civilisation, something that has expanded the abundance of culture, and something that the original form of copyright was not meant to put a stop to (since copyright was invented to serve that abundance, not the creators). Why on earth should content creators get to control derivative works and levy a tax on them? It's absurd. You get paid for your own work, which is what copyright exists for. You should not get paid for someone else's work, even if that other person re-used some of your ideas. Even if (god forbid!) they make a buck with their work?
Screw these entitled content creators; copyright (and moral rights) have been preverted beyond recognition, and need a reform. Not gonna happen though... but I feel not a shred of remorse for authors whose work now gets remixed in AI.