Let's refine the archetype: the pseudo-talented jerk, cowboy coder, workaholic snob.

Demographics doesn't have anything to do with it; it's an attitude problem leading to all manner of manageability and team morale problems. These types of people are unwilling to listen to others and don't consider the needs or abilities of others on the team. They just do their own thing, overengineer things, and knowledge hoard with little or no documentation. It's sad to say but many Ruby developers circa 2011 fit this stereotype because they drank their own KoolAid.