Here is how is works:
Progressive parents convince their children they are gods.
Children of progressive parents go to public school feeling like gods.
Abused children, children of bankrupt business owners, children of farmers forced off their land by environmentalists, children of conservatives with successful small businesses, and children of moderately successful hardworking Americans, all attend public schools with the little gods.
The other children are much different from the little gods, so the little gods laugh at them, bully them, make fun of them, and do everything in their power to remind the other children they are not gods.
Teachers admire the academic success of the little gods, so they support them and refuse to accept reports of their tyranny and terror.
One of the other children, probably from abusive parents, gets so angry they buy a gun, build a bomb, or both.
The angry child returns to the school filled with self-righteous anger at how the little gods treated them and then kills as many other children, both little gods and outcasts, as they can manage. Probably a few heroic teachers get killed too, but the angry child does not care as long as everyone is punished.
After the dust settles, the children of progressive parents (little gods one and all) go on national and international news media demanding someone do something while their progressive parents look on with pride.
Liberal fascism is the real problem. Both bullies and their victims are most often from homes filled with "progressive" ideas, regardless of the economic status of the homes. Progressives create the disenfranchised, then when the disenfranchised lash out violently, progressives quickly blame conservatives.
I am exhausted by both the violent lashing out and the condescension of the liberal fascists. It is liberals who are creating these violent children, and the violent children themselves are primarily from liberal homes.
It's not the gun.
It's not the NRA.
It's not the conservatives.
The real problem is fascism, and in the United States, the behavioral fascists are liberal progressives filled with self-righteous anger at social inequalities they themselves have created and reinforced.
When you demand people mimic your worldview you are telling them they are unimportant. If you tell them often enough, they begin to believe it. Once they begin to believe it, then violence is the only avenue they have left for self-expression.
If you believe some people are scum, then you are part of the problem.
If you believe there is no such thing as second place, then you are part of the problem.
If you believe you are are far more intelligent than everyone around you, then you are part of the problem.
If you believe everyone should behave like you do, feel like you do, and have the same opinion as you do, then you are part of the problem.
If you believe the government is the solution to every challenge, then you are part of the problem.
If you believe humans are all essentially good, then you are part of the problem.
If you believe humans are all essentially bad, then you are part of the problem.
If you believe some people are just better by nature than others, then you are part of the problem.
If you believe you are right and everyone else is wrong, then you are part of the problem.
If your favorite response to someone who disagrees with you is, "That's the stupidest thing I've ever heard," then you are part of the problem.
We are each individual humans. Being human gives us certain needs and certain natural rights. Being human also gives us the ability to make choices. Being human also means our family, our society, the food we eat, the climate we live in, the quality of our teachers, and the skills we develop on our own, will all have direct, immediate impact on who we are, what we believe, and how we behave. Hatred is what drives mass murderers. They learn that hatred from everyone around them.
Somewhere along the line we forgot to be human. Economists and business leaders forgot that if people don't have jobs, then they don't have any way to participate in society, they don't have any way to acquire new skills, and they don't have any hope of a better life. It starts all the way back in elementary school when some well-meaning teacher convinces poor academic performers that they are stupid and incapable of learning so they shouldn't bother trying to study. For every winner there must be a loser and participation trophies only reinforce the idea that losers are lesser human beings than the winners.
Success should not be an excuse for condescension. Success should instill in the winner a responsibility to help others, not give the winner a reason to condemn and criticize. Success that creates humility is good for humanity. Success that creates arrogance is the most destructive force in all of human history.
Work hard, do your best, always look for ways to help those who are less successful without being condescending and without blaming them for their limited achievement.
Encourage. Lift up. Lead with humility. Arrogance and condescension is what creates mass murderers, not the tools available to them.
You reap what you sow. Every single time. Don't ask where mass murderers got their guns or how they learned to build bombs. There is no realistic answer to that question. It is irrelevant to finding a solution. Instead, ask yourself what kindness you can show to the angry, ostracized, socially isolated person sitting next to you. They probably won't appreciate it. They will probably assume you are trying to take advantage of them. But they will remember it and that memory will make them a tiny bit less likely to lash out in hatred. It takes a great deal of kindness to overcome a lifetime of social isolation. That kindness must begin with someone, so it might as well begin with you.