Recently we had this: https://codeofmatt.com/list-of-2024-leap-day-bugs/ So a day for a grocery chain in Sweden and a gas station chain in New Zealand.
For me "There is a 3 out of 4 chance of a damaging earthquake in the Bay Area in the next 30 years." From: https://www.earthquakeauthority.com/blog/2020/san-francisco-... Is this a week of no power (so no cc's, no atm, no cell service).
A cornal mass ejection has 1 in 194 odds, is it bad enough that it's a grid killer? I don't know what the odds are for that (as in having EMP), and its gonna be fun if we see it coming to!
A major payment processor failing, or payment network failing for a few days is possible. What happens when a grocery chain is open and suddenly "cash only". It has happened before.
You dont need a big, or national event where social order is maintained but cash is essential to keeping things moving.