Not responsibility, but body maintenance. Also, I think it's a little bit past the "young jocks who didn't know better". It's been widely known for at least 20 years that tobacco is horrible for your body. It's just completely counterproductive for an athlete.
I have the same view for musicians as well. I will never understand why a singer or horn player would smoke. Your instrument/money maker is your voice and you are directly destroying it through your habit.
Maybe I'm just different, but since I was young, I also thought taking drugs was pretty stupid. It's expensive, it's horrible for you, it often makes you act like an idiot/look like an idiot, and worst of all, you are supporting companies that are RAPING you. Tobacco companies purposely try to get people hooked on poison so they can get filthy rich. I don't want to be one of the suckers they are stealing from.