Social media. It infects young people like a disease, and they are all day every day exposed to it unfettered and have unadulterated access to the worlds perverts, ignorant and hateful people. They pay more attention to others lives than their own.
Disregard for American morals, values, pride and standards.
Public displays of disrespect, biased, hatred, intolerance, and bias by the MSM, public figures and politicians towards police, white people, christians, conservatives and so on. Those public displays tell Americans that it's ok to hate others.
Disregard for the nuclear family. A mother, a father and their children. As that dynamic disappears you see children raised improperly.
Political correctness, forced diversity, and racism disguised as anti racism have hampered institutions including schools to the point they can't enforce rules on children, hold them accountable or punish them.
Radiclization of anger. Politicians and the news constantly talk about anger. They glorify it when it serves their needs, and they glorify it when it happens against them in order to condemn their enemies or justify their actions.
We raise soft, weak willed, pussy ass bitch kids. We don't enforce rules, don't demand personal responsibility, don't teach morals and standards. We tell them all nothing is their fault and how amazing and special they are.
We encourage dumb, thug, gang, ghetto mentality. We let it thrive so kids see it everywhere on social media, they listen to mind numbing music glorifying it, and so on.
There are dozens of reasons why all of the sudden school violence ramped up a lot. It wasn't anything like this 10 years ago. So basically all of America's current problems are because of everything that has changed in the past 10 years because up till 10 years ago we had 100 years free of these problems so it's obvious something changed.