A: You take on a challenge in the work place for the same reason you do anything else, ever: to show up those less talented and to impress the opposite sex. Occasionally, you might take on a challenge to seek the approval of a dead parent, or fictional cowboy, but such instances are few and far between.
There's really no better way to make yourself feel better than by pointing out the shortcomings of others. And there's no better way to do that than to take on a new challenge, achieve fantastic results, and throw it right in your co-workers stupid little faces. You'll get some bonus points of the soul if you are able to point out, in great detail, why you succeed where they fail. You might also want to work out a victory dance, and accompanying song.
The men will fear you, and the women will flock to you. Often two at a time. That's when the benefits kick in.