Damage is Damage, But Different Damage is Different

Putting carcinogens into your body can result in mutations that lie dormant for years. I had a co-worker who fell in her classroom and broke her knee. They X-rayed her for broken ribs but found a lung cancer the size of a golf ball. She had quit smoking 19 years earlier. They removed half a lung and several years later a tumor was found around her spinal cord in her neck. They could not remove all of it. Another few years went by and she developed a brain tumor, which was removed, rendering half her body paralyzed. In all probability, it all stemmed from her smoking. 

As for the drinking, I had half a dozen friends from high school who began to drink at age 15. By age 20-21, they all developed fibrosis or cirrhosis of the liver, and had to stop drinking forever or die. That was 1973. At our high school graduation, 30 years later, five of those guys were doing well in life. Whatever medical problems they may have shared (like Bipolar Disorder in one) was unrelated to their alcohol dependence. The sixth guy just surfaced recently. The others all thought he was long dead. Not! He's married, has kids, is OK. We're all 60 years old. Too much liver being destroyed will require a transplant (not an easy thing to get or a guarantee), but I've clearly seen people survive for decades, once they stop drinking.

I realize that this is neither a medical or a statistical response but a personal one. Genetics is a huge factor. I disagree with your statement, and think that smoking greatly increases one's risk for certain kinds of cancer (throat, lung, pancreatic for example). Of course, I had a colleague who died from cancer of the mouth and never smoked, so this kind of thing does happen. I've heard physicians say that 50% of smokers do develop life-threatening diseases such as cardio-vascular disease, emphysema, or cancers. The other 50% suffer from diminished health of various sorts, often with the loss of skin elasticity, early and excessive wrinkles, yellow teeth, gum disease, stained fingers, etc.. Loss of energy, stamina, and a compromised immune system from regular destruction of Vitamin C from tobacco smoke reduce the quality of life in my opinion, and there is the negative social effect on non-smokers.