http://www.rcpsych.a...mentalhealth.aspx
The Royal College Of Psychiatrists would disagree with you. The link above has lots of references.
I'm not stating an opinion on whether it's any more or less harmful than alcohol or tobacco, but to pretend that cannabis use is almost health-consequence-free is misleading, in my opinion. I think you should be allowed to use cannabis, but to do so in full possession of the facts. And the facts seem not to be that "cannabis has no long or short term mental health consequences", which is what I think you mean when you say "Psychosis: Bullshit, disproven".
What follows is a snippet from the linked page:
Mental health problems
There is growing evidence that people with serious mental illness, including depression and psychosis, are more likely to use cannabis or have used it for long periods of time in the past. Regular use of the drug has appeared to double the risk of developing a psychotic episode or long-term schizophrenia. However, does cannabis cause depression and schizophrenia or do people with these disorders use it as a medication?
Over the past few years, research has strongly suggested that there is a clear link between early cannabis use and later mental health problems in those with a genetic vulnerability - and that there is a particular issue with the use of cannabis by adolescents.
Depression
A study following 1600 Australian school-children, aged 14 to 15 for seven years, found that while children who use cannabis regularly have a significantly higher risk of depression, the opposite was not the case - children who already suffered from depression were not more likely than anyone else to use cannabis. However, adolescents who used cannabis daily were five times more likely to develop depression and anxiety in later life.
Schizophrenia
Three major studies followed large numbers of people over several years, and showed that those people who use cannabis have a higher than average risk of developing schizophrenia. If you start smoking it before the age of 15, you are 4 times more likely to develop a psychotic disorder by the time you are 26. They found no evidence of self-medication. It seemed that, the more cannabis someone used, the more likely they were to develop symptoms.
Why should teenagers be particularly vulnerable to the use of cannabis? No one knows for certain, but it may be something to do with brain development. The brain is still developing in the teenage years  up to the age of around 20, in fact. A massive process of Âneural pruning is going on. This is rather like streamlining a tangled jumble of circuits so they can work more effectively. Any experience, or substance, that affects this process has the potential to produce long-term psychological effects.
Recent research in Europe, and in the UK, has suggested that people who have a family background of mental illness  and so probably have a genetic vulnerability anyway - are more likely to develop schizophrenia if they use cannabis as well.