Consider for some it's already hit home in the form of job loss, which for most people can easily be catastrophic. Or maybe they've a giant datacenter in their back yard suddenly, and now their air and/or water isn't viable.
That of course isn't justification, but it does partly inform why some people are that mad, and it's much easier for angry people to be callously indifferent.
If you were to break down HN's zeitgeist, it's some percentage site-local, some percentage larger tech scene, and some percentage general public.
Although you have outsized influence on the former, the latter items factor in heavily—sometimes overwhelmingly so. You can't really control that, and I don't feel it represents some sort of failure on behalf of the community nor moderation team.
I see it not as mob mentality so much as as multiple sides personally involved for different reasons. Things tend to get pretty heated when that happens; not a good recipe.
I'm sorry you had to deal with the aftermath. Your flurry of disappointed, exhausted-sounding comments reminded me of a service industry worker getting hit with a huge rush. There's a kind of PTSD that hangs around once the dust settles.
So, thank you for your efforts in trying to keep the site civil. It clearly ain't easy sometimes.