Most people get it all wrong and don't realize the big picture of it. Something something liberals. Or "This is what you get when you vote Democrat for 50 years". However that wasn't the problem at all when you look at the bigger picture.
Basic Summary: Detroit was a huge city that relied on a single industry which hired unskilled and uneducated workers for jobs that paid well. Looking at you Bible belt and Appalachia. Ever been to places where there used to be a coal boom? Dead.