Wouldn't it be nice if instead of just bars with alcohol, there were establishments for people to consume cannabis while eating, playing board games, and socializing?
If anything, cannabis seems like a much better (and more profitable) drug around which to build a leisurely establishment.
I don't care about cannabis consumption in public but anything that produces smoke or vapor should be treated the same way as cigarettes. Second hand smoke exposure needs to be minimized.
I am also not sure they would be more profitable. Alcohol is dirt cheap to produce and bars charge insane amounts for it. A $10 bottle in the supermarket frequently goes for hundreds of dollars. A cannabis lounge might be more profitable right now because there is very little supply but I doubt you can have anywhere near the amount of bars or clubs.
For vapor, note that many dangers that you have heard of are related to ecigs (liquid-based vape pens). The ones that are flavored+have nicotine and added adulterants (glycol/glycerol at least), and that use a conductive heating coil that may expose the user to heavy metals especially if they get too hot (though probably more of an issue for heavy daily use). Plus with the higher water content, breathing in the steam cloud may be a lung infection risk.
For a dry (herb) vaporizer set at a temperature under 200C (and convection-based), you don't have those problems (2nd paragraph). I am not saying anyone should be near random people with this, but in a dedicated location it should be fine (especially with fresh/filtered air or an open space). You're breathing significantly worse stuff being exposed to the ambient car exhaust to/from said location (also: gasoline vapor at gas stations).