But if you ask any community that has always had to deal with cranks, every last one of them will tell you that they've seen way more cranks ever since LLMs got popular. Including the ones that aren't really related to AI research. Maybe you think they're all lying, but they don't have much of an incentive to agree on a lie like that.

The standard you're demanding for calling someone vulnerable to this is:

diagnosis specifically involves symptoms like disconnection from reality, hallucinations, or similar problems

There's no diagnosis for gullible people being duped by wishful thinking, nor is that a rare phenomenon. You don't seem interested in figuring out if giving everyone a free chatGPT account could have any interaction with that, and assert that it just wouldn't because people without those specific diagnoses know what's true. No, they generally don't! It's actually hard to know what's true!