There is a direct social cost in terms of health care, law enforcement, crimes committed to obtain drugs, fallout from broken families resulting in further dysfunction and more.
Then there is also the unseen cost of lost productivity. If users, deceased users, imprisoned users, distributors, deceased distributors, imprisoned distributors, and law enforcement personnel were not engaged in these activities, their efforts could be focused on more productive areas of the economy. We all pay for this policy socially and economically.
Alcohol is everywhere. Alcohol consumption correlates heavily, like crazy heavily, with assaults, rape, murder, domestic violence, accidents, and serious or fatal car crashes.
Weed is now legal or legal-ish in many places, essentially all of the big population centers in N. America. Edibles and vapes mean you don't even have to smell it.
And let's not forget all of those articles about SV wunderkunds "micro-dosing".
The addicts that the OP was discussing have serious withdrawal issues and are, compared to things like booze or marijuana, trivial in terms of overall population.