Agreed... Personally think it is from how they are growing up believing they are entitled to everything...Greedy for most part. They think all for themselves. Sad, school fail to educate the importance of respect and accept if being rejected. Nowadays younger generation seems to have trouble dealing with rejections.
But it does not reach the root as to why, when they are denied, is their first response to adversity is to grab a gun and shoot them.
You peg it on the '60s... And this time frame does show a lot going on that affects this conversation... I do agree with your time stamp even though school shootings happened prior to this date.