They're even more rare in the military than in the general population. Firstly for the obvious reason - they don't need any of the benefits so they don't join. Secondly - someone that becomes that wealthy while serving (via a trust-fund, large inheritance, or winning the lottery) would no longer be a good fit for the military. They usually get offered an Honorable Discharge. However, if they still desire to serve the remainder of their term, they can place the money into a blind trust.