Fire insurance claims. You'll recall that Ankh-Morpork burned down when the Tourist introduced an innkeeper to fire insurance. But it's not all fiction: it's odd how the last recession made textile warehouses explode into flame. This article relates recessions to car fires. But one can go too far: surely the recent recycling warehouse fire in New Zealand was entirely accidental. (UPDATE: and Findus' Crispy Pancake factory, too - htp: Henry North London)
Another factor is holidays. How many schools burn when they're empty?
We should therefore (a) all be rich and (b) never take a holiday, especially (not) with children.