"Nicotine is just caffeine" is too clean given the tumor-promotion evidence. To a large extent, it comes down to the method of delivery: patches are difficult to get hooked on because they do not cause a rapid spike in nicotine levels and are not associated with any ritual; cigarettes are hard to give up due to that spike, the accompanying ritual, and the MAO inhibitors found in the smoke; while vapes occupy a middle ground—which is precisely why they help some people quit smoking but foster addiction in others.