I sure as hell don't. It bothers me when every time something like this happens, the question is always, "How could we have caught this?" or "how can we make sure she didn't get a gun?" or "how could we have institutionalized her?"
It's much more useful to talk about how to come to terms with the absolute chaos in our world and structure your life around the principle that the world is a fragile and dangerous place. Anyone can drive their car across the centerline. Any two-bit dipshit can learn how to make aluminum powder bombs and terrorize an entire city. Some crazy incel can walk up to your office and fuck your whole life up as you're leaving for lunch.
This will always be the case. I don't understand why people think it's reasonable to suggest that we can ever live in a world where your mortality isn't seriously exposed, or that it would be a world that would be nice to live in. Unless you're completely out of your fucking mind, most people are incapable of truly coming to terms with it and going about their day, willing to die at any time. Everyone else is afraid, and probably always will be.
I think some people cope with the fear by deluding themselves into thinking security is just around the corner, if only we can just fix a few things like gun access and mental invalids. We just need to do a few things just a little bit better, and then it's all going to be great. These people live in a fantasy world.
Others cope with the fear by isolating themselves and their families, avoiding cities and anyone unlike themselves, maintaining a small circle of trust, neanderthal style. This is antithetical to classical liberal values and thus is unappealing for most young and open-minded people.
If you think you reject both of these approaches, I think you're probably just in denial.