So why do these shootings happen so often in the United States?

[AkSaber]

I would say it's our fascination and enjoyment with violence.

Look at the character of our people. We enjoy violent entertainment. Movies which horrify, say people in Europe, are revelled here. And let's face it, most people in this country enjoy war. They like the thought of kicking someone's ass for some perceived wrongdoing. There's no more settling disputes over discussion. Like, "If you don't agree with us, we'll kill you" sort of thing.

We're all exposed to violence, from a very young age. Most of us just aren't appalled by it anymore.