> Wikipedia summarizes Guillem et al 2005 as "Technically, nicotine is not significantly addictive, as nicotine administered alone does not produce significant reinforcing properties" - the addictiveness coming from MAOIs (eg. Khalil et al 2000, Khalil et al 2006) & possibly other compounds present in tobacco; while there don’t seem to many human studies aside from the Amsterdam et al 2006 review on the observed inhibition in smokers (consistent with the MAOIs playing a role in addiction), there are a number of significant animal studies:
https://www.gwern.net/Nicotine
Not to say it's not addictive at all, I'm mildly addicted to nicotine gum, to about the same extent I'm addicted to caffeine (if it's available I'll certainly take it, but if I run out, I'm not rushing to the store to buy more).
Maybe regulation is a good idea.
How about we only regulated things which are proven to be harmful?
https://www.scientificamerican.com/article/is-nicotine-all-b...
Let's put it this way: are there any scientific studies with results indicating that nicotine, by itself, has significantly stronger self reinforcing properties in comparison to caffeine.
The answer is no: there are none. Quite the opposite. Nicotine has pretty weak self reinforcing properties for all the hype. The magic is in tobacco smoke and various other drug interactions that result in the strong self reinforcing properties of tobacco smoke. So, when many people bring up nicotine's addictive properties they're really talking about tobacco smoke.
There's also the hand-mouth habit, but I digress.