The cause of every mass shooting is the shooter(s) having tunnel vision because other influences have put the blinders on them. Everyone blames the shooters. I blame everyone else involved in their lives. One couldn't simply tell a baby "if you are hungry, there's food in the fridge" and expect them to fix it themselves. One couldn't feed a child shit and expect it to grow healthy or grow at all.
These shootings will not stop until we stop making people feel like shit. Drugs make people feel good and loved. Unban all drugs and the mass shootings stop. Setup safe-use and therapy centers for the destructive drugs to ween people off them (and maybe on to less destructive ones like WEED if they need a FIX). What happened to all the love in teh sixties? IT WAS BANNED. UNBAN DRUGS so these kids can smoke a green bowl and stare at the wall pondering the existence of their immortal souls instead of killing off the good people of this world.
These are just some ideas.