Morgan Housel writes on “once in a lifetime” events:

Think about 100-year events. One-hundred-year floods, hurricanes, earthquakes, financial crises, frauds, pandemics, political meltdowns, economic recessions, and so on endlessly. Lots of terrible things can be called “100-year events”.

A 100-year event doesn’t mean it happens every 100 years. It means there’s about a 1% chance of it occurring on any given year. That seems low. But when there are hundreds of different independent 100-year events, what are the odds that one of them will occur in a given year?

Pretty good.

If next year there’s a 1% chance of a new disastrous pandemic, a 1% chance of a crippling depression, a 1% chance of a catastrophic flood, a 1% chance of political collapse, and on and on, then the odds that something bad will happen next year – or any year – are … not bad.

It’s always been like that.

“Sometimes it feels like terrible luck or that bad news has new momentum,” Housel writes. “More often it’s just raw math at work.”