This is my understanding, simplified as much as possible, of the state of knowledge of "nicotine addiction"...
1. I think it is indisputable that cigarette smoking leads to intense dependence of *something*
2. There is a lot of evidence that nicotine is the culprit, of course, because nicotine has always eased the pain of smoking cessation, in whatever form it's done (and FDA approved or not). Another duh moment.
3. There is also a huge amount of evidence that it is far more than nicotine. Words you will rarely if ever hear: "I just quit smoking and I am totally relaxed and comfortable with my NRT/Vaping replacement". No, what you hear is something to the effect "yes, the nicotine helps, but there is something seriously missing, I'm still craving cigs and I'm a basket case".
(I'll admit that some people claim to start vaping and make it sound like it was easy peasy but I'm not inside their brain and easy peasy can be relative, plus we all seem to experience the various dependencies differently. So maybe I need to modify my "rarely if ever"?)
4. A number of studies have been done where people were given essentially NRT products to infuse smoking levels of nicotine in their bloodstreams. This for periods of 6-9 months. My understanding is that it is a fact that NONE, ZERO, of these hundreds of subjects reported withdrawal at the end of the study when their nicotine was discontinued. That, I think, is conclusive proof, as best we could have at this time, that nicotine, by itself, does not create dependency within a 6-9 month period of regular use.
5. It has been argued here, by people that I personally have no respect for, that inhaling nicotine will have a different outcome. Supposedly due to the greater speed of absorption by the lungs. I have no respect for them because I have seen them argue anything, for the sake of argument, to advance an opinion that is not backed up with any facts at all. BUT...
6. Keeping an open mind, and not wanting to diss a message based on my feelings about the messenger, let's accept the possibility that inhalation is different.
(I do not buy the inhalation theory, short of actual evidence, because it is my understanding that the majority of nicotine absorbed while vaping is done through the mouth, nose and throat tissues, not the lungs. This is very often discussed here, and I assume that to be true. If it is true, then Nicotine Gum and Lozenges would have the same basic effect as vaping since the nic from the gum is absorbed through the same mouth, gum and throat tissues. The effect of the less effective lung absorption *shouldn't* make much difference, but our lab rats will prove that one way or the other)
I will also add that I've seen nic gum users talk about the "fast hit" they get from the gum, and my long experience with nic gum was similar. In my experience there is no faster and deeper "nic hit", aside from smoking, than chewing a tab of 4mg nic gum.
Now we are left with our lab rats, in the form of never smoking vapers, to basically test the following two theories:
1. Nicotine, by itself, might create dependencies over longer periods of time (many years) than the studies covered. And, in theory at least, the studies I mention were not intended to test dependencies, they were testing for neurological benefits. But if nicotine likes to form dependencies, outside of tobacco use, it shouldn't care about the motives of the people that organized the studies
2. Test the "inhalation theory" I mentioned in #5.
Now, as I understand things, in fact there is a great body of experimental evidence concerning long term use of nicotine sans tobacco, in the form of long term never smoking users of NRTs. NRTs have been over the counter since 1996, 19 years now. As best I understand it, although there may be a few isolated cases reported, few if any never smoking users of NRTs have been reported to have significant dependencies.
If I am correct in my facts above, there is not a whole lot (new) to test here, there is 19 years of experimental data out there. But if my facts are wrong, let's discuss that.
A habit? A hobby? A dependency? An addiction? 
