I think you are misinterpreting what I am trying to say. I agree that most people smoke marijuana because it makes them high. That's the whole point of smoking it. Some people may feel badly afterwards, some don't, and some don't ever make the connection - so they continue to smoke. I know people who smoked most of their lives without any problems. All I'm saying is that smoking is OK for some people, and a really bad choice for others, if they are negatively mentally impacted by it.
I don't claim to pinpoint the cause of "schizophrenia". Quite honestly, I don't believe in the label. All the different labels for psychiatric mental illnesses which are listed in the DSM (around 300 of them) are just labels for a specific set of symptoms. The labels themselves are the result of a bunch of psychiatrists attending a convention, often in a nice resort location, who vote on which symptoms should constitute the next new psychiatric 'illness' – and all for the sole purpose of prescribing a particular medication to treat it, and getting insurance companies to pay up. That's job security for psychiatrists. Even the nation's leading mental health official, Dr Thomas Insel, director of the National Institute of Mental Health, attacked the DSM-5 for a "lack of validity".
On a practical level, as soon as people have a mental illness diagnosis in their medical records, they can have trouble purchasing a fire arm or getting insurance or certain jobs or a security clearance. It also changes how people think of themselves.
People are labeled "mentally ill" when all they have is a variation of normal human behavior, or a temporary psychotic episode resulting from any number of possible causes, one of which might be a genetic sensitivity to psychosis from THC.