This is a bit of a tricky question since it speaks to the contrasting viewpoints of addiction versus the consequences of personal choices. My personal viewpoint is that where the accountability lies depends greatly on one's age. For older people, smoking cigarettes was a part of the culture. In decades past, the dangers of nicotine and smoking were much more hidden from the public while at the same time tobacco smoking was much, much more socially accepted. It was so socially commonplace that tobacco products were advertised and sold much more widely than today, and major celebrities and public figures could be observed smoking on television, movies, and advertising. And while it may seem somewhat obvious in retrospect that directly inhaling the smoke of burning embers might not be the best idea, the combination of the addictive qualities of nicotine coupled with universal social acceptance is a powerful combination to resist. So older people (50's and above) get more of a pass from me. I have commented before that when I was a kid in the 70's/80's, it was much more commonplace for the parents of my friends to be smokers rather than having a tattoo. Now those social trends have been completely reversed.
For people my age and younger (40's and less, particularly for people in their teens and twenties), the accountability lies squarely with the person. People of this age grew up in an era of the knowledge of the dangers of smoking and that nicotine addiction can be on par with drugs like cocaine and heroine for many people. These people grew up in an era when major public figures spoke out against smoking and tobacco was made more restrictive and taxed at a much higher rate to discourage smoking. When I see a young person smoking today I shake my head because they are making the decision despite the fact that the negative aspects of nicotine are common knowledge today (not to mention that it costs a small fortune). They really have no-one to blame but themselves.