Minnesota has more alumni than Michigan, the state's a little wealthier, and a lot of other things are essentially equal.
The big thing they have is an enthusiasm gap. They start by filling a stadium over twice as large as ours, and they have a lot of "Wal-Mart Wolverines" (fans who didn't go to Michigan, live there, or have any connections) all over America. At the moment, Michigan also benefits from being the only Detroit-area sports team that is doing well.
I've seen a couple CFB sites do charitable drives and chart the results by school and Michigan wins almost every time.