aparatchik
An aparatchik is someone who enters a pre-existing human hierarchy (like a corporation, a government or an online Forum) purely for egotistical reasons of his/her own. In other words, they have no sympathy or interest in THE ORIGINAL TOPIC OR CAUSE for which the corporation, government or forum was created; rather, they simply see the hierarchy as a ladder by which they can cynically achieve their own selfish aims (money, power, visibility, etc.)
The city politics of Finetown used to be so interesting, as its founders were passionate crusaders who truly wanted to create a utopia; today, however, Finetown's council is filled with bored aparatchiks who just seek to get ahead and make money without accomplishing anything.