It is not healthy. Even without scientific research, anyone should be clear that the inhaling of any smoke can be harmful in the long run. Scientific and statistical research supports it even more. Many diseases are caused by smoking. These diseases attack your lungs, heart, arteries, veins, throat, etc…
It harms others. You are aware of so called passive smoking, but do not understand it too seriously. On the contrary, somewhat arrogantly you complain about any ban of smoking in public places because, ultimately, they may have compromise your rights. And where are the rights of other people? You would rather kick out of the shop non smokers than the cigarettes. On top of that you are trying to justify it by your own reasons.
It is expensive. Cigarettes cost. Most of you will complain almost daily to about your inadequate salary, but you'll still buy cigarettes. Why? You do not take the money from yourself only but also from your family. From the education of your children. From healthy diet. From better living standards. From enjoyable vacation and travel. From your economic security.
It smells bad and it is dirty. Look at your nails, teeth, skin and hair. Smell your clothes, curtains, stifling air in the living room or even bedroom. Are you hiding bad breath by taking even more smoke? Your breath can be a bit repulsive to other people.
You support harmful industry. A huge amount of money goes to the tobacco industry. That makes them so rich, therefore they can control the government and pass legislation in their favor. It makes the economy dependent on it so the government cannot endanger it. Another huge amount of money go off your salary and moves into the health system, due to illnesses related to smoking. At the same time cigarettes are accessible all around. Is not it a bit absurd?
It encourages others. Directly and indirectly, you do not know that you do it. You present the smoking as something completely normal, in certain situations, even attractive. The impossibility of giving up is somewhat "cool". This is all a game, right? It is not. Grow up. Because of people like you children starts to smoke. You are to be blamed for it.
You think you can stop. This is what most of the drug addicts thinks too. You think that you are in control. Most of you probably are not. You will stop only when (and if) you are all really got sick of it. In that case the quitting will be long and arduous. In worse case you will become ill and you will quit immediately upon the diagnosis, but that may be too late.