I doubt the number of people experiencing this is anywhere close to what Wikipedia says it is. I know a lot of people who have used a lot of psychedelics from their late teens to 30s/40s and none of them have had HPPD
Only one of the studies Wikipedia included had concerning results, and it was a survey of users. Such studies are good indicators of where future research should be done, but only demonstrate a loose correlation between psychedelics and HPPD. There’s no differentiating users who are “self-medicating” the issue from psychedelics causing the issue.
AFAIK this is not something that's seen with psilocybin, maybe with frequent high dose LSD... Anyway, I wish people didn't even bring this up because it'd be a shame if that dissuaded anyone to try psilocybin.