There is no such thing as smoking just a little. Cigarettes are the one legal product that can kill when used exactly as directed. It can kill not only the user, but people around that user who have no intention of using that product themselves. They are forced to “smoke” as non-participants.
Even were it not assur to kill oneself (v’nishmartem m’eod es nafshoseichem), it most certainly is unquestionably assur to cause harm/potential death to another person. Anyone who believes it does NOT cause harm to others, after all the reports that prove otherwise, is simply a thoughtless, inconsiderate person, whose negligent and depraved indifference to life in pursuit of his hano-ah, demonstrates a singular self-centeredness that is not consistent with Torah values. Our Gedolim who smoked made a few mistakes back in the day, because they were unaware of the serious and life-threatening ramifications of smoking, or they would have paskened differently. Today, I doubt a responsible Gadol would say it’s perfectly OK to smoke. And the exhorbitant amounts of money used to buy the smokes, could surely be put to far better use, don’t you think?