as of 2012 roughly 47% of American households contained at-least one gun.
so, no, 'most' people don't own guns, but on average every other person you encounter on the street owns a gun.
the point is that effective gun safety is as easy as effective scissor safety. it's no more complicated, difficult to remember, or difficult to implement, the safe handling of a gun than than to safely handle scissors. those who accidentally kill themselves with guns did not truly have an accident, they chose to not learn, and abide by, basic safety rules, and were rewarded with negative consequences for their actions. there's nothing 'generally' wrong with taking a gun selfie, what this guy did is no different from taking a car selfie, and forgetting to put his car in park so it rolls over him while he's taking the picture.
it's up to the individual if they choose to educate their children regarding firearms safety, considering that there are 300,000,000 firearms in America, and that 47% of homes contain firearms, it's a useful, and easy to acquire, skill.
you don't need to touch a firearm to learn the rules of gun safety:
ALWAYS keep the gun pointed in a safe direction. This is the primary rule of gun safety. ...
ALWAYS keep your finger off the trigger until ready to shoot. ...
ALWAYS keep the gun unloaded until ready to use.
but, there's always the option of not educating children, because it'll never happen to
my kid.