Isn't nicotine harmful?
Nicotine is not the harmful ingredient in tobacco, it is the smoke that kills: the smoke and combustion artefacts cause lung cancer, heart disease and many other illnesses. Also, everyone tests positive for nicotine in the bloodstream, in very small amounts, since it is a common ingredient in vegetables. A related material, nicotinic acid, is a vitamin - Niacin or Vitamin B3 - so to say it is universally harmful is obviously untrue.
Without the smoke, 'smoking' is likely to be far less harmful, as nicotine may be as harmful as the caffeine in coffee. Nicotine is best avoided by those who are pregnant or have heart disease. You may want to avoid it if you also do not take caffeine or alcohol by drinking coffee, tea, wine or beer. Like these substances, it should probably not be started in the first place. Some people however find their lives are dysfunctional without nicotine, and an electronic cigarette is probably as good a way as any to supply it.