It is not compulsory to smoke, drink or use intravenous drugs but many people do, for those who indulge to excess it will more than likely shorten their lives and may even kill them way before they reach their normal life expectency...I don't have any problem with that whatsoever, it is their choice, as long as they do not cause me to go to an early grave.
I'm not picking on you but this is exactly what I am talking about. People are automatically assuming that all smokers go to an early grave.
It is a risk, yes, but not automatic or guaranteed.