I might add that, at least here in the U.S., statistics indicate that a fairly high percentage of people that experience an addiction to the "heavier" drugs began their drug use with cannabis. Additionally, recent studies have shown long term, irreversable brain damage after prolonged marijuana use. The question arises as to who will pay for the care of individuals who experience, of their own will, such addiction. The numbers of people that would follow such a course, at least intuitively, would increase significantly if control was abandoned totally...
It seems, for some reason, that most of the population can use alcohol on a limited basis without becoming addicted, hence no expense to society. However, the expense to which we're subjected by the individuals who do become alcholics is significant, no?
A friend, who is law enforcement here, has given me a great, first hand education on the effects of production and addiction of methanphetamines. It's use, only once, produces such an emphatic "high" that most users are hooked by that singular experience. The effects are truly startling and destructive to the user... and we all wind up paying for it one way or another...