It is the only legal substance that, when used exactly as is intended, can still kill you. Alcohol does not do this. When taken in moderation, no harm will come to the drinker. But the smoker can develop a host of illnesses and maladies from just one cigarette per day. This leads to another point.
Tobacco is the only legal substance that can become addictive when taken as designed, as well.
It is impossible to smoke just one cigarette a day. You may start that way, but eventually it will escalate. That is why the tobacco companies target teenagers. The earlier you start the more cigarettes you can smoke before they kill you. Nothing can bring back the grandmother that I never really had a chance to know, and nothing can save my cousin from the disease that grows within her lungs, but there is still time to help my friend and the millions of other young people that are both smokers and nonsmokers alike.