What about the "My body, my choice" mantra I keep hearing?
Is tobacco bad for you? Yes, but so are french fries and coke. Obesity is the second leading cause of death in the US. Are you okay with applying a "sin tax" to what you eat to discourage you from buying it? Or charge obese people more for health care? Or deny health services to you if your BMI is over a certain amount?
And, of course, then we can apply the same principle to any inherently dangerous activity, such as, oh, swimming or mountain climbing or motorcycle riding or taking a shower (every day, someone in the US dies from an accident in the tub or shower...) ????
So please, do the math, indeed.
p.s. I don't smoke, and not obese, just pleasingly plump...