No benefit of any kind to anyone?
Jesus, the arrogance of this guy. What makes you think you can make such blanket statements about everyone's experience like this?
Cigarettes are great for getting a boost of energy, or for having an excuse to talk to a stranger. And sure, both of those are things that we shouldn't need in a perfect society because we should all have enough time and calm to sleep and mental health care to get over our social anxieties. But that's not the society we live in--we live in a society where we can't be arsed to provide insulin for type 1 diabetics or school lunches for children. Giving nurses reasonable hours or high school students realistic dating advice aren't things in our society. So you'll have to excuse people for using the fucked up solutions that are available rather than the perfect solutions that aren't.
I'm not even a cigarette smoker, I just have a basic sense of empathy.
According to our shared oral mythology about bootlegging gangsters, yes. According to all available crime and health data from the time it was an incredible success.
Crime fell. People got healthier. There was less domestic abuse (people forget that temperance was first and foremost a women's movement). None of this was outweighed by the increase in organized crime.
Prohibition was a "failure" in the sense that people like alcohol and do not wish it to be illegal. It was not a failure by any other definition (boogeyman stories about "organized crime" notwithstanding).
This is easier to see if your baseline is, "excessive alcohol consumption is a societal disaster" (which is the correct baseline). Prohibition would have to generate a staggering level of harm to match the existing harms of consumption.