I'd say they strive to be fast because they judge everyone else and expect to be judged by everyone. It's the way they see the world working for everyone - the way it works for them. In reality, no one gives a sh!t about 5k times outside of a small slice of the population. And it congregates right here, worshiping the altar of obtaining validation by comparing clock times.
This is the corner of the world where this viewpoint is the most prevalent - the place that seems the most "normal" to some folks. Happens with all fringe viewpoints. This site's fringe viewpoint is: "running fast says a lot about a person and shows they are worthy of respect and admiration". It isn't shared by the world at large, so an internet sub-community forms.