most flights don't have every single person show up. there might be, say, 2 or 3 seats unfilled even if you sell every seat on the plane. so instead, sell a co

most flights don't have every single person show up. there might be, say, 2 or 3 seats unfilled even if you sell every seat on the plane. so instead, sell a couple of seats twice, and bet that not everyone will show up. if you're wrong and everyone shows up, you have to pay people extra to take another flight, but that apparently happens infrequently enough that overbooking makes money over the long term.