By that rationalization, OpenAI is paying their Internet bill, and for a copy of Dune, so they’re free to use any content they acquired to make their product better. Your original argument wasn’t akin to, “Shouldn’t someone using an iPhone pay for one?” It was “Shouldn’t Apple get a cut of everything made with the iPhone?”
You could make the argument that people use ChatGPT to churn out garbage content, sure, but a lot of cinephiles would accuse your proverbial indie movie of being the same and blame Apple for creating the iPhone and enabling it. If you want to make that argument, go ahead. But don’t pretend it has anything to do with people getting paid fairly for what they made.
ChatGPT is enabling people to make more things, easier, to get paid. And people, as always, are relying on everything that was created before them as a basis for their work. Same as when I go to school and the professor shows me lots of different works to learn from. The thousands of students in that class didn’t pay for any of that stuff. The professor distilled it and presented it and I paid him to do it.
Everyone will take whatever advantage they can from any result. Apply previous sentence to any scenario.