In the reply you replied to, you can see that I am writing about how they may know the dangers but may not know to what extent the danger is (probably because they always wake up the next day). For instance, if a doctor told a smoker that his lungs are so damaged that one more cigarette, he’d be dead, I can guarantee you that the addiction will vanish because now he knows that it’s to the extent his life would be gone in the next try.
As already said, most of them know about damage made by cigarettes. I really doubt that words like that one more cigarette could be last one would stop him. Now in my country on package of cigarettes there is images of damaged lungs or something similar, not sure how much it helps.
Probably they don't stop as long as they feel ok and don't get lung cancer. Though, my grandpa even with lung cancer didn't stoped smoking almost until his final days...
Many countries seem to do that for the sake of awareness about the damage it can be done to our inner organs by the continuous consumption of tobacco smoke. Here in Venezuela, it is not only oictures of damaged lungs, our authorities have gone ever further than including pictures of tumors and destroyed teeth embedded on the cigarette packages. Though, the tax of tobacco seems to be relatively low here, since people continues to smoke regardless of the accumulated prices though the months.
By the way, I am sorry for what happened to your grandfather. It seems there is people who truly are willing to through some of their time in earth for the sake of satisfying their craving for nicotine. Hopefully he did not suffer much from that disease...
I had a family member (sister of my grand mother) who also liked to smoke much and she even liked to smoke with the lit extreme of the cigarette inside her mouth. I never understood such a thing.