Ironic docs who smoke & drink

A lot of students coming into med school smoke and drink, which is fine since that's your choice. The irony is in that they didn't fully know of the consequences of smoking and drinking until they took biochemistry in 1st term of med school. I keep hearing people getting surprised, "Oh! I didn't know smoking and alcohol could do that! Can't believe I'm still alive!". Some students have the belief that alcohol is more dangerous than smoking, so it's okay for them to smoke - this is the logic they use.