People could now possess a device that would accurately propel a small piece of metal faster than the speed sound for purpose of killing living things from a distance. The power that represented was phenomenal. It changed warfare from set piece battles to prolonged and exponentially more lethal wars of attrition. It also allowed a person possesing one of these new devices the power of life or death over others in a way unseen in human history. A pistol fits in a pocket, a rifle over a shoulder, and allow the bearer to kill from a distance whereby the risk to themselves is minimised and the kill is or incapacitating wounding of their target or bystanders is very nearly assured.
That kind of power is incredibly seductive to a fearful-minded and untrusting tribal primate only a few evolution-years out of the caves and trees.
Somewhere along the way the possession of that power became normalised, as if Remingtons, Glocks and AR15s always existed and aren't products of culture, ingenuity, and economics. For some, the gun became part of their culture and even their indivdual identity. Some nations put them on their flags, some people insisted on the right to carry them anywhere they pleased. Governments passed laws allowing greater or lesser distribution of firearms depending on the sentiments of their varying electorates.
The narrative of the gun and the empowerment it gave the individual spread with other techologies. Cinema genres evolved around the lone
However within all this mythmaking, real people used their gun-provided godpower to kill other real people. The ready access to firearms made it possible to walk into a workplace, a school, or a street and kill whomever one wished, while other people argued and lobbied for the 'right' that made firearms available to murderers.
The cost of 'gun-rights' are massacres, murders, and accidental deaths. Arguing for looser controls on firearms means that you're willing to accept that periodically someone is going to walking into a school or workplace and kill a lot of people. It means that somewhere some toddler is going to accidently shoot themselves or their sibling. It means that somebody's spouse is going to die after abuse or rejection.
Gun-rights also mean that small arms industries do grow to the point where economies of scale make light weapons and ammunition easily affordable in the poorest places on Earth. Places where warlords flourish and mass graves fill.
Firearms are a social attractor. They are something that members of society for differing reasons congregate around because they have value to those members. In order to limit gun violence two things need to happen. The physical attractor, guns, need to be removed from play. The second thing that must happen is the reduction in the symbolic value and therefore importance of firearms. Yes, guns are a large part of certain cultures, but cultures are not static and the things they value can and do change under the right conditions. Turning gun-fanatics into social lepers, combined with severe restrictions on firearm types, sales, and distribution will go a long way to removing their importance. It could be done in under a generation.
The gun culture of today did not exist 150, 50, or even 20 years ago. It emerged with advancements in firearms technology and the progression of culture, war, and economics that followed the metal cartridge and it can disappear when the social impacts of those developments are no longer tolerable. It does not have exist 20 years from now.