Alcohol certainly contributes to depression. It also causes a great deal of social harm. If you heatmap crime in a city bars are often the epicenters of violent crime. Factor in that the majority of sexual assaults and domestic abuse cases involve alcohol and I'm not sure what your argument is.
Alcohol contributes to depression in excess, in small regular quantities what harm is there?
> If you heatmap crime...
Again, look at all the problems I had with your original arguments. Alcohol is legal, and hence there is far more opportunity to abuse it. Small, regular amounts of alcohol is likely not be be harmful at all - all problems arise from excess, hence there is an argument for restriction, not criminalization.
Why are you talking about alcohol rather than marijuana in any case? Your comparison is a straw-man - whatever can be concluded about alcohol doesn't necessarily apply to marijuana.
Why are you talking about alcohol rather than marijuana in any case?
Your assertion was that legalizing cannabis would cause social harm. If your goal is preventing harm then you must also criminalise the currently legal recreational drugs to be logically consistent.