But it isn't. It's the carbon monoxide, that thing that causes the little tingle when you haven't had it for a while, that is really addictive. Which is what kills you.
Consider this. An e cigarette will give you in average a much stronger hit of nicotine than one cigarette. However some smokers say they aren't the same. Of course they are, but they haven't got the other hundred chemicals and added excitement of a glowing ember. It's all in the mind. I'm not playing it down, I struggled to stop smoking myself, but once you realise what you are actually addicted to it's easier to break the habit.