It should also be noted that public health officials are usually the lowest rungs of the ladder when it comes to ability in medicine. Running your own practice, running a research institute or chair or even just working in a hospital is far more interesting financially as well as for the challenge. Becoming a public servant as a doctor is a way out when your marks are just above passing or your motivation is insufficient for anything with even minimal amounts of stress (of course not atm, but that is an exception).