Unfortunately, we also have lost our moral compass as well. We have become a culture of 'I want it now and don't want to have to work for it' as well as being force-fed propaganda by the media of what the ideal life should be. So to afford this, most kids are sent off to public school systems and then into daycare to be raised by people other than their parents while the parents (assuming there are even two at this point) come home from work almost too worn out to care.
As we all know, kids will act out for attention. They get in trouble, get attention and when ignored, any attention is bad. Or worse, 'little Johnny' is too wild... so lets pump him full of this crap to keep him calm.

Guns aren't the cause of this, and these shootings aren't people trying to act out as violent military heros. If that was the case, they wouldn't be gunning down innocents.