you have to sell it (or deceive for material gain) for it to be fraud.

You could argue that you did that to entertain your social media followers and gain more of them, which is somehow a material gain.

For starters people pay for ChatGPT accounts used to generate these things. Secondly people use ChatGPT to generate stuff they put up on social media slop accounts to earn money. You'd probably build a case by finding a collection of these to justify discovery for more and build your fraud case based on that kind of thing where people are generating and publishing work with your signature on it for money. That's both a criminal and civil case.