So how can we talk about it?
While the particular event that collapses a system may be unpredictable, the susceptibility of a system can be observed by how fast that system recovers from a traumatic event. The longer the system takes to return to homeostasis, the weaker the system.
This behavior can be observed in all sorts of systems: society, family, ecology, economics, health, ect.
For instance, a person starts taking months, instead of weeks, to get over simple illnesses or injuries will often succumb to a more serious problem like a hip fracture, even though a healthy person would still recover from it.
Note that many economies are taking longer and longer to recover from stress, often not even fully recovering anymore. I suspect a lot of things could push them over the edge now. For instance, imagine if the USA population moves 25% of it's wealth to cryptocurrencies. In the past, I think the USA would withstand the stress, today I doubt it.