I consider Public Health to be a dangerous pseudoscience. It should not be confused with epidemiology, which is a real and respectable science. Most "public health" work is really a superficial and shallow attempt at legitimizing a left-wing political agenda.
Most importantly, an MPH will not significantly increase your earning capacity. What are you going to do? Run a clinic for indigents in the inner city? Do "public health" research at a university? Sit on one of the newly created "Death Panels" where you can play around with comparative effectiveness research? If you do any of these things, $150K/year will be your glass ceiling, and I'll happily wave to you from above it!
"I swear by my life, and my love of it, that I will never live for the sake of another man, nor ask another man to live for mine." -Ayn Rand