People always say "well alcohol is worse than marijuana, and alcohol is legal, so marijuana should be legal." Problem is that same logic can be used to say "well marijuana is not as bad as alcohol, and marijuana is illegal, so alcohol should be illegal."
It's why stating alcohol being legal while marijuana is illegal as justification for marijuana legalization holds no weight. The logical structure does not specifically support marijuana legalization, and can easily be used to justify alcohol prohibition. You need to provide more substance to the argument, otherwise you're just commenting on how the laws are logically flawed. Prove that it should go the legalization route, and not the prohibition route.