Luke Kemp, a research associate at the Centre for the Study of Existential Risk at the University of Cambridge, has written a book about his research called 'Goliath’s Curse: The History and Future of Societal Collapse'.
He makes the case that, from looking at the archaeological record, when many societies collapse, most people end up better off afterward. For example, people in the post-Roman world were taller and healthier. Collapse can be a redistribution of resources and power, not just chaos.
For most of human history, humans lived as nomadic egalitarian bands, with low violence and high mobility. Threats (disease, war, economic precarity) push populations toward authoritarian leaders. The resulting rise in inequality from that sets off a cycle that will end in collapse. Furthermore, he argues we are living in the late stages of such a cycle now. He says "the threat is from leaders who are 'walking versions of the dark triad' – narcissism, psychopathy and Machiavellianism – in a world menaced by the climate crisis, nuclear weapons, artificial intelligence and killer robots."
Some people hope/think we are destined for a future of Universal Basic Income and fully automated luxury communism. Perhaps that's the egalitarianism that emerges after our own collapse? If so, I hope the collapse bit is short and we get to the egalitarian bit ASAP.
Collapse for the 99% | Luke Kemp; What really happens when Goliaths fall
It is really nothing compared to what will happen if the current international infrastructure supporting hospitals and food delivery breaks down.
Most people don't grow their own food, they buy it from a store. There's about a week, maybe two of fresh food in the system, depending on local population density and available suppliers. Maybe a month or two of dry goods.
Hospitals are highly dependent on consumables to provide care. In a month they're out of exam gloves, masks, sample tubes, hand sanitizer, antibiotics - then sanitation starts to break down and hospital-acquired infections start to ramp up. Less time for high-value items like anesthetics, immune suppressants and other specialty drugs. The volume of chlorine and isopropyl needed daily just to keep things clean will be a problem. Anything less than immediate life-threatening conditions starts getting turned away because the hospital is a source of danger for otherwise healthy people, and they might not have the resources to provide care anyway. The emergency room runs out of blood bags.
In the present, the things that keep people alive are dependent on just-in-time logistics systems. There's very little inventory stored anywhere, because it's cheaper to not store stuff. If the trade relationships break down and the supplies become unreliable, it falls apart. And it doesn't have to all come to a complete halt for people to die, it just has to become unstable so that sometimes the right things don't show up at the right places at the right times.
Systemic collapse would lead to orders of magnitude more deaths.