A negative anecdote: a friend of a friend of a friend went on a retreat and did actually lose his mind. He needs help and probably will for the rest of his life. Just putting it out there for some balance. I’ve heard my fair share of positive anecdotes too.
So some guy on the internet says that a friend of a friend of a friend of his lost his mind on Ayahuasca? Based on schizophrenia rates, I suspect pretty much everyone even has a friend of a friend that might catalyze their latent schizophrenia through psychedelics. But, the idea that psychedelics cause mental illness in those that otherwise would have been fine is not supported by scientific evidence[1][2], only anec…
Anecdote or not, and regardless of the causality argument, taking a substance can "catalyze" such conditions to use your wording. There are numerous accounts of people who truly were/are "never the same" after taking LSD or similar substances.
It's important for people to understand this, because of chicken vs. egg. If someone has such a predisposition and isn't aware of it, they might engage in ingesting such substances under the pretense that a substance cannot "cause" a mental illness, meanwhile believing there's no way they could have any such disposition. Contrarily, understanding that these chemicals absolutely are permanently-life altering, regardless of any pre-disposition, is probably the most important thing to consider when weighing pros vs. cons.
Speak to anyone who has taken LSD or similar. Whether good or bad, whether the person is mentally stable or not, the common thread is that changes in mentality/perception from taking these substances are permanent.