If I might add something to the discussion: the $210 million initial donation is not what is directly funding the Gates scholars. Instead, it is the return on this investment that is used for funding. For most trusts, the initial donation is never distributed, so there will always be $210 million at the Trust's disposal, which they invest to earn the funds they distribute. It is likely that the cost difference between funding only PhD's and funding only MPhil's is negligible compared to the effect of the market, so seeking diversity in their scholars plays a larger role when determining the mix of successful PhD and MPhil candidates.