Imagine a person seeing loved ones — former heavy smokers — painfully die from lung cancer and emphysema, and BECAUSE OF THAT going out to buy a carton of cigarettes… or a deadly car wreck convincing you to go straight to the auto dealer…
In other words, the most negative impact of a product driving up demand for its purchase. Sounds absurd, of course, but that is what happens with firearms in the US: their worse consequences (mass shootings, gun homicides) make people want them more, not less.