"better mental health care"
Unfortunately, the science for reliable mental health care doesn't exist. We're not even close.
Therefore, habitually violent and threatening people.... be they thugs, bullies, autistic kids, or the mentally ill.... need to be identified and "marked" such that they may not access firearms or other weapons.
Most schools are well aware of their "bad boys", but the fact that they have Special Education labels makes their violence private..... and so we routinely release them on society.
The numbers of the thug-diva-mentally ill types is growing. Parents are failing to parent, and kids that would normally just be a bit flakey are turned into monsters.
This, in my opinion, is a new phenomenon and this first generations of these tempermental kids are just being released within the past 10 years.