Not fully sure this is that, but it reminds me of something an American friend explained about their business under the Trump regime (as a rant about how laypeople were deeply under-reacting to the tourism decline):

If it takes 100 tourists to pay his bills, taxes, staffing, and other expenses for the day, the next 5 tourists represent the profit. A tourism decline of 10% doesn’t mean 10% less profit, it means the catastrophic inviability of the whole business as it’s currently structured.