I have to agree with shahkg. Get an MPH if you are interested in public health, and you have the resources to do it. Education is not a "waste". An MPH may not help you with technical skills acquisition, but the extra education may help you become a more critical thinker. You will learn to use statistics, and gain skill at evaluating research/papers, and that is a very important skill for anyone. There are surgeons with MBAa, PhDs, etc... One of my attendings has an inordinate amount of training... he completed 3 fellowships... and he once told me that he regrets not training for an additional year before becoming an attending. He said that in retrospect a year is a small temporal price to pay for expanding one's educational horizons.
We are in a field that requires us to pay huge sums for our education, and so it's understandable to think of education as a means to increase our earning potential/opportunities. That's appropriate to a degree. However, if you want the MPH training, and have the resources, then do it. It WILL make you think differently, and perhaps make you a better physician/thinker.