I don't smoke because:
- it smells bad and I get agitated when I smell it.
- it's not healthy
- it isn't cool
- you become addicted to nicotine and you can't stop then (I mean you can, but you have to try hard!)
- you are agitating others because of bad smell
I think it's enough points to be non-smoker.
But I know what it's like to be addicted to something and I understand their need for it, but, hey, the smell, they might do something about it!