Edit: well you edited your comment twice since my reply, so I'll be right back with some information for you.
Overall synopsis: http://www.drugabuse.gov/publications/drugfacts/cigarettes-o...
Mainstream overview: http://www.huffingtonpost.com/2014/01/17/cigarettes-more-add...
> Nicotine is a drug found naturally in tobacco, which is as addictive as heroin or cocaine: http://www.cancer.org/cancer/cancercauses/tobaccocancer/ques...
Onset of addiction: http://abcnews.go.com/Health/story?id=117976
Finally, understanding addiction of nicotine: https://tobacco.ucsf.edu/content/featured-study-understandin...
I experienced zero addiction for the first three months, and even after the full two years addiction was mild. I reduced my dose gradually over two weeks. There were no physical withdrawal symptoms, and only minor craving which went away after a few months abstinence. I'm no expert on heroin addiction, but I find it hard to believe it's equal to nicotine. Perhaps whole tobacco would be different.
It springs from the interaction between the two; different drugs have different addictive qualities, different people have different susceptibilities to those addictive qualities. Individual extreme outliers -- in both the more easily addicted and less easily addicted directions -- for any particular drug are to be expected, and don't disprove the general feature.
The only people who claim that are ones who haven't been addicted to cigarettes :-)
If you're only smoking once a month, the nicotine isn't building up enough to make withdrawal a problem. I'm not even sure there's enough nicotine in one cigarette that you would notice any withdrawal symptoms. And in a month, the nicotine from the previous cigarette is long gone.
Besides that, the hardest part of quitting is getting rid of the habits around it, and if you're only smoking once a month, you're not forming any habits. Try smoking a cigarette with your coffee first thing every morning for 6 months, and see if you still believe it's not addictive :-/
That said, I'm sure the strength of the effect can vary from person to person.
I do agree with you that the occasional cigarette can be very pleasurable.
I feel as though the addiction springs from the person and not the drug, just as some people are addicted to gambling or facebook or video games. Some people just get addicted to anything that once gave them a positive emotion.