Why An Over 3,000 Ft Building?

The Kingdom Tower in Jeddah, Saudi Arabia, is 3,280 ft (1 km). But why a building so tall? I think it's because people want to show what they are capable of. But I think that people can't breathe when you're building over 3,000 ft in the air. But anyways, it's a great building. Here's a rendering from Wikipedia.