I grew up in a house where both my parents smoked... and drank. Granted, I have a natural immunity to alcohol, but I smoke cigarettes because my drug of choice isn't legal. Seeing as how they are working as hard as they can to make cigarettes as easy to get as say, a supermodel with a good personality.
I'm working on quitting before the government tells me I can't smoke anymore. Thanks to the PACT act, it's getting entirely too prohibitive to get them at a decent price. My mom needs to quit. She's got a horrible smoker's cough, but she's at the age that she farts when she coughs. Totally has ruined the humor of farts for me for a while.
Besides, it's not like I have a wife or a girlfriend or kids to worry about killing with secondhand smoke. So as long as people are just killing themselves, let them. So far that isn't illegal.