There must be something seriously wrong with those of us who chain vape 36mg+ and feel fine for the most part
Aside from the whole stimulant-tolerance thing, you might just have a liver that is, like your Chuck, customized for nicotine intake:
Nicotine is metabolized, like many drugs, by the cytochrome-P450 liver enzymes, and there are many genetic polymorphisms governing how fast you metabolize through each enzyme. Some people are "cheap dates", i.e. they have very little of an enzyme and therefore a lot more of the original drug stays in their bloodstream for longer. Others are so-called rapid or ultrarapid metabolizers through an enzyme and their liver converts a drug to its metabolites very quickly.
So, if you have a polymorphism that makes you a more rapid metabolizer through CYP2A6 or CYP2B6, the main enzymes breaking nicotine down into cotinine, your liver might be going through that nicotine like a blast furnace.
(I am
not a doctor, just a patient and a geek since I was a wee one. This is pretty much
speculation ported from knowledge of how other drugs/enzymes work.)