1) When you had droves of Europeans moving in to "settle" the "discovered" land (not the people, just the land), they came across groups of folk who had been here for a LONG time (like a millenium) and had their own ways of doing things and carving out territory. So eventually, conflict was settled with the superior technology (the gun) and a lot of chicanery.
2) Years later, the settlers became colonies, and the colonies got fed up with paying off the cousins in the old country. Divisions were made, you had a revolution, which required everyone keep guns just in case the neighbors got uppity.
3) The settlers had pretty much beaten down the original inhabitants, but their slaves (imported) would be a threat to up and leave for greener pastures or just plain revolt. Thank goodness for the guns to give to organized policing of these people. And then there was that Civil War about slave owners wanting to keep things as is to insure their economic stature. Bang, bang!
So we're scared of each other, everyone is either holding grudges or wanting retribution for generations. So it's not surprising that you get rhetoric in response to repeated and increasing mass shootings.
