Gun is a fetish symbolizing power and control over others, and that is the main appeal of gun ownership to the majority of the US population. Self-defense is just socially acceptable rationalization. American culture emphasizes power and control yet the life of most people in the US is subject to a myriad of regulations, both private and public, that leave individuals basically powerless against institutions, corporations, banks, credit cards companies, government agencies and so on. On the top of it, the paranoid style of media reporting and political discourse creates an illusion of constant and imminent danger ranging from common crime and natural disasters to uncertain economic future, to lack of social safety net, and to a myriad of bizarre conspiracies. The end result is that people who are culturally expected to be in charge and in control sense that they have little of both and fear that they are in constant danger by some looming threat regularly dished out by the media and politicians.
From that pov, buying a gun is a ritualistic behavior to buy peace of mind and sense of security in a society where people feel constantly threatened and having little or no control. In other societies, folks would be buying talismans, lighting candles, saying prayers or making sacrifices to the gods to secure their safety, but in a secular society such the US gun ownership plays the same ritualistic role. It is a mental crutch that gives troubled and scared individuals a false sense of security and peace of mind. Taking that mental crutch away is seen as cruel and senseless as taking a crutch from a disabled person.
Debunking the myth of defensive gun use will do little to reduce the appeal of gun ownership to the majority of the US population. To do that, you need to implement far reaching social reforms that would instill a sense of personal security, social safety and control of institutions and the political process. People who feel that their environment is safe and secure and that they are empowered to control that environment and their destiny in that environment do not need to rely on fetishes giving them illusions of that safety and control. Unfortunately, the oligarchy that rules this country will not allow such reforms to happen any time soon, and instead will continue relying on fearmongering to manipulate the populace.