How come some of the most intelligent people settle for the lowliest positions?

Unless you are in the stratosphere with your intellect, networking is generally a better indicator of success, barring some extreme incompetence (although that doesn’t necessarily stop everyone).

So people that have money, connections, and charisma are probably going to do better with career advancement than someone that’s typically the smartest person in the room. Plus intellect doesn’t always translate to career ambition; a smart person can be happy or content with a lowly position that requires genuine effort, as opposed to a higher position that is mostly presentations and office politics.