Marijuana has been portrayed by the drug culture, with enormous funding from George Soros and his billionaire pot-smoking buddies, as an innocuous substance when, in fact, it is insidiously and extremely dangerous.
In the past fifteen years there have been numerous studies from all over the globe reporting on the significant role that marijuana plays in causing or exacerbating psychosis. It has become a leading reason for those seeking or assigned to drug treatment, and is a leading cause of drug-related emergency room episodes.
One well-designed and controlled study found that pilots trained on a flight simulator could not land a plane even 24 hours after smoking one 3.5% THC joint. Today's pot is much more potent than that. And did you know that it is also a leading factor in male infertility? It causes premature apoptosis of sperm and egg cells. And the list goes on and on and on.
Those who advocate for pot legalization insist that they can "handle" the drug. Likely most heroin addicts and meth addicts thought that they could handle the drug as well. The cost to society of their addiction, violence and crime, unemployment, under-employment, increased illness,etc., is borne by the rest of us - and it is in the hundreds of billions annually.
As for your libertarian view that this is a right, when our children were small I told them that the only time they had absolute freedom to do as they please would be if they lived alone on a desert island. If another individual came along then they would likely have to devise rules to live together in peace and safety. And the more people that came to the island then then more rules they would have to make. Having rules is what makes a civil society work.
Without them you have anarchy. Surely you do not support anarchy? And surely you would not advocate that just because a person believes themself to be the world's best driver they should be free to drive at whatever speed they choose whenever and wherever they want? I thought not. You are dead wrong on this one.