This requirement from your school sounds very cheezy to me. Why would anyone pack USD50K in the expectation that if his funding is rescinded, then there will be something to fall back on?
Maybe, you are speaking with the wrong persons. I'd get in touch with the head of the international students office. Its not a even a requirement for visa, so why would they ask this of you? Imagine if all the US universities were asking int students to show proof of 'just in case' funds.
Sorry that i'm ranting about this, but it sounds silly to me, unless there's something (like they use the initial funding to lure students and then revoke it after the students matriculates ) they are not telling you!!!