Schizophrenia and bi polar disorder both have strong genetic components so messing about with brain altering substances is risky at best if you have a family history of mental illness.
It’s also true that this could be a chicken/egg issue. Is it the drugs/alcohol that caused the psychosis or do people sliding into mental illness gravitate to drugs/alcohol to self medicate.
Having worked in the mental health system, I have met a lot of dope loving mentally ill people that quickly stop taking their anti-psychotics in favor of pot. The problem is that pot isn’t an anti-psychotic and eventually they go batshit again.
Of course, nowadays, we just let them live on the streets of Portland and Seattle instead of locking them up and getting them back on their meds.
Thank you for some reasoned comments on the subject.