Because smoking causes many, many more health issues than any other habit, stressor, or factor you could come up with. There are the obvious diseases of lung cancer, COPD, throat cancer, emphazemia, hight blood pressure and heart attack. Then you have the ones that aren’t usually associated with smoking like bladder cancer, kidney cancer, strokes, and the lists go on. All of these diseases and cancers are long term and costs billions of dollars in treatment.