One thing that I can definitely say in a blanket statement about 99.9% of all smokers who defend their habit to the death in every discussion, is that they uniformly change into the worlds biggest group of sorry hypocrites when they get a major smoking-related illness.
Those who know it's bad and keep trying to give up, deserve sympathy and support. As for the dedicated smoker who keeps arguing smugly, well they keep their heads in the sand until the last minute and there's no combination of words or phrases that will change their mind. You have to remember how stupid, gullible, peer-influenced they were to start. That kind of pig-headedness cannot be debated away.