What drives home size?

Americans like large homes. According to the National Association of Home Builders (NAHB) the average size of a new single-family home has grown from 983 sq. ft. in 1950 to 2268 sq. ft. in 2006 (of course, waistlines have also grown significantly since 1950). While more recently the recession has helped slightly reduce the average square footage, homes in the U.S. are still enormous by global standards. Many people around the globe might even assume a home such as this one under construction in Connecticut (significantly larger than the national average, but similar in size to neighboring homes) is intended for dignitaries or members of a royal family.

I actually don't know the specifics of this particular home and it's possible that it's being built for an extended family of 12 people. However, more likely this home is being built "on spec" by a contractor and will eventually be inhabited by a relatively small American family. In such a case, the contractor would have paid a large sum for the land (and existing home if there was one) and wants to build the largest home possible to get the best return on investment. Of course, to realize that return the home must be sold and so there must be demand for such homes. What's drives demand for such large homes? Frankly, many people buy homes far bigger than what is required for their actual family size to demonstrate their status in society like some ancient ruler erecting an ornate palace as a signal and reminder of the ruler's power. Another factor may be a desire for isolation from the community (no need to go to town when your home boasts a media room, library, gym and commercial kitchen) and even from family members themselves (family interaction is minimized when every member has 1000 sq. ft. or more per person).