Obviously more people will try it if it is legal, but it's pretty ubiquitous now and most adults have already had the chance to sample and decide.
As for the "cost to society", I have to imagine that any damage from use (and there's not much evidence for it) would be countered by the decrease in real damage done by the War on Drugs.
I doubt that. How many people try cigarettes for the first time the day they turn 18 or alcohol at 21?
Anecdotally at least, people first try these substances when they want to, not when it's legal for them to do so. I can't imagine this being significantly different for marijuana - it's already so easy to obtain as an illegal substance.
Anecdotally, alcohol and cigarettes are substantially more widely exposed to minors than marijauna is. That will likely change when everyone's older brother can pick up a bag at the store.
Exactly. And I would further argue that the possibility is very high that it will actually decrease alcohol consumption, which as we all know is immeasurably harmful.
Marijuana is the one that is immeasurably harmful. The biggest benefit of legalization is that it will allow us to make good measurements of the effects.
As for the "cost to society", I have to imagine that any damage from use (and there's not much evidence for it) would be countered by the decrease in real damage done by the War on Drugs.