I live in Ireland and only recently was a Brazilian man found not guilty of murder by reason of insanity after developing cannabis-induced psychosis and stabbing his girlfriend. There was another case in California of a woman who stabbed her boyfriend over 100 times.
Having a sister that works as a psychiatrist, she has always been concerned about how many young people seem to have a 'laissez-faire' attitude towards cannabis and other hallucinogenic drugs. They seem to think that because cannabis, LSD, and mushrooms aren't physically addictive, that the risks are non-existent or overblown.
The majority patients of hers who present with drug-induced psychosis usually get it from smoking cannabis.
I'm all for legalization but people don't seem to realize that with certain genetics, it can trigger a psychotic episode. It baffles me how many people try and deny the link between it and mental illness in people susceptible to it. They'll usually say "you didn't smoke cannabis". When it comes to alcohol, people would tell someone who got in trouble drinking that they need to cut back or give it up altogether as it's probably not for them.