There is some regulatory nuance I believe that makes them harder to buy than regular vaping products but I forget what it is — a simple fact though is that the social aspect of smoking breaks, smoking at bars, the habit of smoking is a huge draw and it's hard to replicate that with gum.
The best product to solve the nicotine crisis is a smart device that gradually lowers the nicotine invisibly to the user over a 3-6-12 month period. This isn't a super hard problem, the FDA and the market is just too non technical to execute.