What do you do with 72,000 square feet?

Jeff blogged about Workday last week. And while I don't have any real insightful thoughts on that yet, I did come across this article on Peoplesoft and Workday founder Dave Duffield. Among other things the article mentions that Duffield evidently wanted to build a 72,000 square foot house in Alamo, CA. However, after protest from the HOA he "scaled back" to 21,000+ square feet.

My question (and keep in mind, I live in Manhattan): what do you with all that space? Now it seems he has 6 kids; so if all kids lived with Duffield and his wife, that would be 9k sq ft per family member. That compares to a US average of 2266 sq ft per house and 872 per family member. A Duffield kid would have gotten 10X the space of a "normal" American kid. In the reduced version of the house, they will "only" get 2,625 each. Well, they probably have a lot of toys.