If I may be welcomed to mediate here, I think the two sides of this argument are based on unrelated points.
Guest or multiple guests, Want to know why people choose to smoke despite overwhelming evidence that smoking cigarettes can lead to illness and death. This is not necessarily a logical question, because the fact is people don't smoke because the benefits outweigh the risks, simply put, they enjoy taking that risk. The point that smoking causes an addiction is really quite relative, because realistically if a person wants to stop smoking, they can. These people choose to smoke and it is their right to make that choice. The fact that that choice doesn't make sense to you is valid, but because the argument is to smoke or not to smoke it becomes an issue of choice, not reasoning.
I don't think that Psy is in denial about how smoking is hazardous, however he reserves the right to do as he pleases as long as he does so without hurting anyone else. His point is on his freedom of choice and that people who cling to the anti-smoking campaign exert a pushy judgmental attitude about other peoples personal choices. Its really an underlying issue, and we could be substituting any other substance or risque act as the subject matter here but it all boils down to the fact people tend to get pissed off when people tell them to stop doing something that is their personal choice to do so.
For instance, if i wanted to go get "Shitting Dick Nipples" tattooed to my face I'm sure you would have many reasons as to why that isnt a good idea, but it is simply not your business to tell me what I should and shouldn't do. Maybe my lifestyle is different from yours and while you would never get "Shitting Dick Nipples" Tattooed to your face, (for obvious reasons) The fact that I would be willing to take that risk is my choice and mine alone. Just the same, if you are a male I'm sure you probably look at porn, If I stepped in and told you how horrible the porn industry is and how immoral and gross it is to be looking at that don't you think I would be crossing the line by judging you and your personal choices?