Well, yes that's one. I don't see how somebody could live happily knowing they caused a loved one's cancer with their actions. But even worse could be the damage your body has to put up with. Many older people who smoke or smoked are very weak because of damage their lungs took in the past, so weak and so damaged they have trouble just walking, and have to use a machine to do an simple task like breathing. Not to mention the damage in self confidence from having terrible skin and teeth.