What would you call a person pejoratively who is on a professional privileged position such as Engineer, geologist, senior engineer etc (earning what the post demands) but chooses to do a job of a say a postman or peon or secretary or a clerk and get away with it.
In other word he is doing work below his responsibilities (without affecting the remuneration). Enjoying perks of the position but responsibility of a assistant.
PS: The responsibility he has for himself assigned is because of privileged position of being "the one-eyed man is king in the land of the blind". No one is able to notice it.