There is a difference between using something (and getting used to it because it increases your quality of life) and a chemical addiction.
> The chemical/psychological distinction is hardly important.
There is a huge difference. If you are addicted to something it is pretty much a physiological effect on you.
Simple example, the addiction of the adrenaline rush and dopamine release of extreme sports.
Most physiological addictions have a psychological component. As an example, I'm addicted to caffeine, but I'm also dependent on coffee as part of a morning routine. Smokers who are addicted to nicotine are often also dependent on the social aspects of being a smoker. It's often the psychological component that, long term, is the hardest to break.
The converse, however, is not true. A good example is so-called "Internet addiction" which should rightfully be called "Internet dependence", at best, because it has no physiological component.
Smoking is expensive, unhealthy, inconvenient, and stinky. That's why there's a big push to get people unaddicted to smoking, but not so much push to get people unaddicted from caffeine.
Honestly, I liked smoking a lot (still do really). I disliked the addiction.
"Quit Smoking the Easy Way" by Alan Carr
Yes, it is. In some cases, withdrawal can cause death.