The main complaint I see in the comments (I cannot help it, I like to see how the majority of the world thinks) is major health condition. Do these people not carry health insurance or does it not cover most expenses? Mine seems to.
Unfortunately, I have recent first-hand experience of how medical issues can sink your ship, however carefully you've steered it over the years. For me, it's a chicken-egg thing. I always had gold-plated health insurance through the Fortune 500 co. I worked for. Nice income, low insurance rates, most things covered, max out of pocket 10k, no problem, because I have a stash and still had hefty income coming in.
But lose the job due to medical disability, go onto half pay disability (if you're lucky, and that can run out or be denied by the long term disability insurance at any time), and get bumped to the Fortune 500 co's "retiree" rate plans... Wow, now instead of $400/mo for a family of 3, I'm up to $700/mo for the same plan. OOPMs are higher, and now I'm trying to keep my head above water with copayments and OOP expenses on my half pay disability... It starts to feel a little tenuous... especially if you're in an open-ended health situation where you don't know how long you'll be unemployable due to health (Yes, you can start applying for SSDI, but that can take years...meantime you need a roof, health care, and food).
I didn't see how it could happen before because I always (for decades) had the stability of a good job and (guaranteed, even with a health event) good benefits, and was always healthy before, but now that I'm watching those things slip away to some degree, I can see how people lose the things they worked so hard for over the years when they have the misfortune of an extended health care crisis--and, goodness, especially before the ACA. Get sick, lose job, lose insurance, and try going onto the open market and getting insurance with a pre existing condition. Nope.
Now I'm nervously watching those ACA exchange plan rates go up, wondering if and when I'll need to shop for one (when I get the heave ho out of my co's "retiree" plan), what that'll cost, what the OOPM will be, whether I can keep my really good doctors on any new plan I can afford (integral: good docs who you trust, who know you, you've built up relationships and history with--when you get really sick you don't want to start back at Square 1 with "luck of the draw" doctor).
Honestly, it sucks, and until you're in the throes of it, it's hard to understand. That used to be me too.