No proof, good grief.
If we're going to argue whats good and what's evil, then let's use a standard. If you do something and it hurts you and someone else, it's stupid. If you do something and it hurts someone more than what you've gained, it's stupid. If you do something that helps you more than it hurt someone else, well, somebody still got hurt. If you do something that is mutually beneficial, that's good. Now where would you put smoking?