I've never smoked a cigarette in my life, and I never will.
In fact, I remember the day I was offered my first cigarette. I was in a Tim Horton's just outside my high school in crappy Mississauga. One of my best friend and a ladyfriend he was interested in were having an afterschool chat when she pulled out a cigarette and offered it to us. He accepted; I declined. I understood concepts like "consequence". The three of us were in the Gifted program in school, so it's not like they "didn't know better" or anything like that. He took it because he wanted to be cool in her eyes. It worked, as several months later they dated, had a brief hate-filled relationship, and eventually went their separate ways, both degenerating and disappeared off the planet.
1) At first I was confused and irritated by the minds of smokers because I considered them unintelligent enough to take up such a self-destructive habit, knowing full-well what poisons and toxins they're inflicting upon themselves. When I ask smokers how they feel about dropping 10 years off their lives, and creating misery in themselves in those last 10-25 years of their living due to a severe premature decline in their health, the most common response I get is "I don't care.". Wow, brilliant.
2) Then I loathed smokers. In university smokers would gather inside the protective dual doors -- the only entrance between the parking lot and the main buildings, and smoke inside, creating a hotboxed chamber, and dropping their cigarettes on the floor. I would either be forced to walk through this cloud of poison, or detour some distance through the brutal winter cold to another. I would walk up to them, remove their cigarettes from their hands/mouths, and demand they leave. Or else. Honestly, I don't give a rat's *** what you do to your own body and your own health, but when you subject me to suffering caused by your stupidity, you cross the line, and are extremely inconsiderate in your existence to be doing so. You've crossed the Chemical Warfare line, would you like some equally harmful retaliation? I suspect you would be just as angry.
3) Then I learned that tobacco companies have been screwing you poor folks over for decades by making you chemically addicted, adding nicotine to cigarettes, keeping you weak and defenseless slaves to their products -- much like how a heroin junkie is addicted to the euphoria of his drug. He, too suffers wildly in his lack of access to his drug, just like you do to yours, and realized ok, some of it isn't actually your fault.
However, #3 became less and less relevant, the more I inescapably experienced #2.
You want to know why humanity is fuked? Look in the mirror at your retarded, inexcusably self-destructive habits and how not only are they bad for you, but how they're directly negatively affecting those around you.