Afaik HPPD and schizophrenia are distinct conditions, most people with HPPD don't report any symptoms common in schizophrenia.

Psychedelic drugs push anyone towards a psychotic state, and really can teach you something about mental illness by giving you a view into their world. But yes it can cause psychotic break, especially LSD but shrooms too.

Why did you link that HPPD subreddit? I used to have visual snow a lot, does it have anything to do with latent schizophrenia?

Funny how intolerable are those "latent" diagnostics for illegal drugs, and meanwhile the totally legal and widely prescribed trazodone (an antidepresant) is known to cause, among others 1) suicidal thoughts, 2) insomnia, 3) hallucinations, 4) and paranoia. Other common drug, bromazepan, turns you into a half zombi, loss of ability to remember and amnesia, hallucinations... And it has a bad widthdrawal.

Of course you have to be careful when taking LSD, psilocybin or whatever. But don't replace info with FUD: just study, legalize and put the info in the box when sold. They are not worse than 95% of widely prescribed drugs. They are illegal just because they are also enjoyable.