Suffering from a psychotic disorder does not mean that you are "crazy", and even less violent or dangerous! These illnesses sometimes lead you to have strange behaviours, but with the appropriate treatment and care adapted to your needs, the symptoms are strongly reduced or even disappear. This is why it is important to follow your treatment.
Some people are more likely than others to develop a psychotic disorder (genetic predisposition, environmental factors, etc.). And certain psychoactive substances can trigger psychosis in the brain. This is why, during adolescence, some young people develop psychotic symptoms following cannabis use, while others do not.