Smoking is obviously harmful. How much depends on the person's personal habit, how long they've been doing it, and genetics.
If you get sick and you smoke, it's blamed on smoking even if there is absolutely no relationship between your illness and smoking.
The second-hand smoke risk is greatly exaggerated for the sake of social stigma. I remember doing a research paper about it, looking into the oft-quoted WHO study, and even at that tender age, seeing how sloppy the methodology was, and how unsubstantiated the claimed conclusion was. In full disclosure, I do smoke occassionally, but this was years before I ever smoked (and at the time I was trying to get my dad to quit).
Yeah, I do think it's exaggerated in order to give society a pariah to pick on.
I'm curious as to what proof we have that a society devoid of drugs is superior to one with drugs. And for any proof that someone could provide, I will counter with The Wall and Sgt. Pepper's Lonely Hearts Club Band.
Liberté. Égalité. Fraternité.
1) The drug must have life-endangering/damaging side effects even at standard doses, and/or be addictive to nearly anyone who uses it.
2) The prohibition against it needs to be enforceable.
Pot fails both these conditions.