So, I've heard he didn't actually have UHC. There's also no confirmation of a denied claim, just the fact that he had back pain. Luigi targeted Brian because UHC was the largest insurance provider in the country, not because he was personally denied a particular claim. The guy was doing long distance hiking and running months before the slaying.

TrueAnon podcast has a great deep dive into who Luigi was and what his potential motives were.

He's got a background in Effective Altruism, he got into the Dark Enlightenment movement, and was involved with a number of Silicon Valley gurus with particularly extremist ideology.

Far from simply being an unhappy customer, it's likely he's a real life "Radical Centrist" who got pilled on far center neoliberal ideology.