I don't think he is insane. What he did was wrong but he isn't crazy. We have this tendency to label these people as nuts out of hand and that isn't always the case.
From his POV (and unfortunately a greater percentage of the American public than most of us are comfortable with), he had a logical reason to do what he did. The issue is that things have devolved so much that the patina of civilization that the majority of us adhere to is showing cracks. Having an AI set up to deny claims (which can invariably lead to death and greatly reduced quality of life for people) is something that also comes off as grotesque to a bunch of people.
This goes back to an old logic question I have heard proposed w.r.t. the abortion question: If pro-life people believe that abortion is literally murder, why aren't you violently opposing abortion clinics? And the answer to that used to be that taking the life of these people made you no better than them. And for the vast majority of adherents, that logic has held firm. Someone who argued that type of opinion would be shouted down.
In the case of CEO's and corporate big-wigs, there is a narrative that these people are killing and enslaving you to make a buck. That narrative has gotten much easier to push since we have a bunch of people coming up who have a failure to launch and they need someone to blame and honestly can legitimately point to some stuff that does point back at corporations and elites and decisions made the past 30 years and find support for that narrative. It is a bad thing when people on both sides of a political aisle kind of shrug their shoulders (at a minimum) at an "elite" getting gunned down in the street.
I don't think this guy was crazy. I think he logic-ed himself into a bad decision. He didn't off himself afterwards. He didn't try to hide the murder weapon. He kept his manifesto on him. This guy wanted to get caught. He is going to be an anti-hero for a bunch of people, a modern Ted Kaczynski. I said before that we are nipping at the edges of some really bad stuff. Things can teeter back to normal or a flash in the pan event can turn everything into crazy town. We are in dangerous times and have wholly unserious people (all parties) in charge. That is a danger to us all.