1:
Stop the defensiveness about smoking. It is assur, and will always be, despite how much smokers enjoy the experience. There is no comparison at all with your example of stuffing your face at a restaurant. I hope you possess enough intellect to grasp that. But I’ll make it really simple. Just because overeating carries its risks and dangers, is that a reason to declare food assur? Not an exact parallel, if wearing 5 ציצית would be prohibited because of בל תוסיף, would that render wearing 4 ציצית a problem, too? Now let’s make it even simpler. Food is requirement. There are boundaries and guidelines to follow, and certain foods are indeed assur. Likewise, those things that carry danger and risk are also prohibited, and this includes overeating (whether at restaurant or at home). Smoking has not a single benefit, and only danger. Even if you minimized the danger statistically, the balance weighs in against permitting it. So there you have it. Simple enough?