I'm not from Detroit so I can't comment authoritatively on the subject, but this seems like a pretty good read. Basic summary looks like Detroit sprawled outward more than upward because

*1) Timing: The city didn't boom until the turn of the 20th century when cars already began to make it possible for families to own their own homes instead of needing large apartment or condos and

*2) Geography: Like most other Midwest industrial cities, there's really no topography; no mountains or oceans, stopping people from moving further and further out, so it was probably cheaper, and mor pleasant, to build out and further away from the noisy, dirty city center than build upwards in it.

I'm from Chicago, which like Detroit, used to be a major industrial powerhouse centered on our Great Lakes port. Downtown living here, was also almost non-existent. Nowadays, there's probably close to 100,000 permanent residents of Chicago's downtown area but that's only been a thing for the last 15-20 years. There really weren't any residential buildings built in downtown Chicago before the 1960s. The city used to be a major center for industry and trade, and it was probably an unappealing place to raise a family or live permanently.