It's impossible to overstate the concept of a Single Point of Failure. And how fucking difficult it is to prepare for such events when the only counter is (shock horror) to spend money.
When I was strategising for a major insurance company, I worked on DR/BCP plans that encompassed the possibility that not only would the main office be unavailable, but the fallback rented space (for outages greater than 24 hours) would also be unavailable. The mitigation was to have a preparation for key staff to connect remotely.
I put that possibility under the heading "alien invasion". And sure enough no one noticed the heading. Just the cost. There was quite a heated debate where the Finance Director refused to believe that there was any natural event that could cause two buildings 75 miles apart to be simultaneously inaccessible without warning.
This was in 2015.
As we all know 2020 smashed a lot of flaky DR/BCP plans. And some companies did go bust because of their parsimony.
I cannot explain how impossible it is to explain to bean counters that if you want a 100% efficient organisation, then you also have to accept 0% resilience.