You can set up a temporary pool in a huge venue such as a football stadium and get higher attendance, or stated differently, you can accomodate a one-time need for that much spectator capacity for an event like the Olympics when you will never need that again in the lifetime of the facility.
Maybe not the same level of attendance, but you can build a permanent pool with temporary stands for the Olympics, and use the larger than necessary deck in other ways after the Olympics.
