Tall buildings: Vanity and excess?

Why humans build what we build is a fascinating topic. Living in Philadelphia and now Dallas has allowed me to survey the buildings and structures in the area (Philadelphia building post here).

But, does it always make sense to build such large buildings?

China is in the midst of building the largest building in the world. To add to the boast, they're saying they can do it in three months. If it's a competition, the U.S. has, apparently, dropped out. The United States' largest building (Willis Tower) was built in 1974 and its third tallest, The Empire State Building, was built in the 30's. One World Trade Center has a higher antenna than Willis Tower, but a lower roof height and still won't compare to the highest buildings in the world. The Trump Tower in Chicago was set to be the highest tower in the world, but after 9/11, they backed off
the height. Is America too wise to play the game or just too poor?

There is a design to build a 7,900 ft building in Dubai. To give you a sense of scale:

The Empire State building, the third tallest building in the U.S. is 1,250 ft. For those of you who have been to the top, you know pedestrians look like ants and cars looks matchbox sized. The highest building in the world is in Dubai and stands 2,717 ft tall.

Like art, building a 7,900 ft building doesn't have much practical value besides being beautiful, intimidating, and potentially inspiring. Especially in many of these cities where real-estate is available. Aren't there better things to do with the amount of money it takes to build something like this? Do we really need to be convinced of our scope when we're already dominating everything around us?

Tallest buildings in the U.S.
Tallest buildings in the world
Tallest proposed buildings in the world