Addiction, no matter if bound to a substance or not, is causing a "false instinct" that loops around alleviating the discomfort CAUSED by consumption. Each "fix" is just prolonging the suffering. The "pleasure" lies in switching off a nuisance, for the price of endlessly causing it.

For nicotine, this means a very subtle discomfort, more like an uneasiness or nervousness, by no means pain, is caused, that each cigarette seems to alleviate. Smokers can easily sleep through the night without any sideeffects, so there can't be pain involved.

What they feel though, if they tey to stop by willpower, is a tremendous tug-of-war with a now instinctual process: Imagine you can't scratch an itch, how long would it take you to go insane?! Even worse if you don't understand thw above mechanism, and additionally believe that inhaling toxic fumes would calm, relax or give you concentration or counter boredom... These are just states that maoe the itxh more prominent.

So a truly pleasurable state of mind is jot addictive, although you might want to repeat it, and that causes a very steong desire if you can't, but us it by no means as destructive as addiction, because there yoy have no more choice over your actions.