Exactly. If airlines want to "play the game" by overbooking flights then they need to pay whatever comp is necessary to get someone to give up a seat on an overbooked flight. At some point, someone will take the offer. In this case, I'm sure even if they had to offer $2000 for someone to get bumped it would have been many times cheaper than what it is costing them now. The problem is that United got cheap and stopped at $800, which clearly wasn't the market rate for a seat on that flight at that time.