I do not agree with you as to the relative harms of marijuana and alcohol. If you have any medical evidence for your viewpoint, please post links to the primary sources. And, my broader point remains, that adding another legal intoxicant is not justified by already having one legal intoxicant.
"Of all psychoactive substances, alcohol is the only one whose consumption has been shown to commonly increase aggression. [...] Marijuana and opiates temporarily inhibit violent behavior" - Psychoactive Substances and Violence, U.S. Department of Justice's National Criminal Justice Reference Service
Researchers have been unable to directly observe THC toxicity even in larger lab mammals, much less humans; claims about toxic levels for humans are extrapolations from intravenous administration to mice. Fatal alcohol poisoning, by contrast, is a well known phenomenon.
Your "broader point" remains a straw man no matter how often you repeat it. As I've already explained, my position is the self-evident one that comparably hazardous products merit comparable legal restrictions; if you were taking the position (as a few on FR have) that alcohol should also be illegal, we'd have agreed on the aforementioned common sense ... but you reject common sense here.