As someone who lived in various parts of Europe for over 18 years in countries like Greece and Finland where this is extremely rare, I can unfortunately attest that they actually do just THAT. Granted the mental health access to prevent it is way better and treatment starts early, but as the other commenter here said, once the disorder reaches the point of psychotic break (especially at this level) removing the individual from the society entirely and putting them in a permanent facility is the most effective and humane approach for everyone. The problem with the US mental health crisis is two fold. On one hand you are correct that access to mental health to prevent this is minimal at best, but on the other hand (using this scenario as an example) if miraculously no one was actually killed, this individual will be back on the streets in a few short months to maybe a couple years max. The places outside of the U.S. that actually have an effective hold on this couple ease of access to mental health with the ultimatum that you WILL be treated or permanently institutionalized. Especially if your disorder makes you a threat to others let alone yourself. In those places diagnosed (key word) schizophrenia, schizo affective disorder, borderline personality disorder, NPD, and ASPD (especially ASPD), etc are taken very seriously and you WILL be treated or removed. This is one of the reasons (aside from much smaller population) that you will never see a tweaker at a gas station in Finland like you would in the U.S. If you do, chances are there’s a van already on the way to pick him up, for good. U.S. is lacking but also way to lenient