junglist said..
Why do people smoke? It's because they are drug addicts, pure and simple.
Nah man, there's more to it than that.
1. It's a demonstration of man's ability to harness and control fire, something that sets us about from other animals and makes us what we are.
2. It gives the lungs a bit of what they evolved to get on a regular basis - smoke. Before we lived in houses with climate control we did a lot of hanging out around fires. We evolved to get a good dose of smoke on a regular basis, and modern life takes that away from us (although in some cities that could be argued).
3. It looks pretty cool.