Ideas can’t be copyrighted. Paraphrasing some text explaining an idea isn’t a copyright violation. Having trained on something you wrote doesn’t necessarily imply a copyright violation. It depends on what the LLM outputs.
I think the issue is that it’s case-specific, but there are plenty of people claiming copyright violations in circumstances where there’s no specific evidence for it, and a few other people claiming that LLM inference necessarily means it’s transformative use.
Besides all that: no matter how you slice the actual case for infringement, these companies have the authorities in their pocket and even if what they are doing is technically illegal I fully expect them to get away with it because they are very wealthy. Which is one reason they're not seeing any of my money.