^ Detroit and the auto industry going downhill in the '80s actually was kind of a positive for UMich as it made them realize (before most publics did) that they needed to fundraise and grow their endowment like a private as the public money wasn’t going to be there in the future. And yes, not being under the direct control of the state was a plus.
Compare and contrast with UW-Madison or UIUC, who’s endowments are nowhere as big (and are more under state control).