While it is true that some people have had psychotic episodes triggered by psychedelics, this is an extremely uncommon occurrence and there is no evidence that psychedelics "make" anyone who does not already have latent schizophrenia or other disorders psychotic.

Prolonged use of powerful stimulants is a much more reliable cause of substance-induced psychosis. Alcohol, marijuana, and other drugs are also more common causes of psychosis. The fact that other drugs cause similar states does not lessen the impact of psychedelics, but demonstrates that the commonly held belief that psychedelics make people crazier than other drugs is incorrect.

The plural of anecdote is not data. Anecdotal evidence is essentially useless. Determining cause and effect is another huge problem; it is well known that schizophrenia has extremely high comorbidity with substance abuse disorders. It can be very difficult to determine if the drugs caused the schizophrenia, or if the drugs were used BECAUSE of the schizophrenia.

Unless the data used in this study are incorrect, this study has shown that rates of mental health issues among people who use psychedelic drugs are no higher than among the general population. ie: your conjecture that drug use may pose a significant risk for people later in life is not supported by the data. Nor is your "feel" that incidents of psychosis are more common among psychedelic drug users.

I don't understand how anyone who understands the scientific method can look at a massive quantity of quantitative data and dismiss it all because based on their limited exposure to people with mental health issues, many of them have used drugs in the past.

I have met many people who have mental health issues who have NOT used drugs - does that convince anyone of anything? Neither should the fact that you have met people who have used drugs and had mental health issues.