I don't think the analogy to generative models holds. The possession and consumption of meth and CSAM _drive_ production of meth and CSAM; it's a supply and demand market. So simply possessing it harms others as well.

A generative model is different. You can produce as much content with it as you want, hallucinated out of thin air. The production of said content doesn't have externalities, other than electricity usage, if the content isn't distributed.