Because of your genetic profile the wear and tear theory doesn't apply to you...and I am happy for you. But...most people are not like you and smoking does harm them.
Ever visit a Veteran's Hospital and check in the cancer ward? I have.
http://www.infoaging.org/b-the-4-random.html
Both teams of Doctors even said that my cancers were NOT caused from my smoking!
Good for you, a$$hole. Are you a veteran? I am. Bet you never wore a uniform. Since I did, this country can kiss my ass with their bans.
Have you ever considered veterans have been exposed, in general, to a heck of a lot more toxic things than a cigarette? Has anyone studied that?