3 Questions about "Detroit"

1)- Why did things start to change in the 1970s and early 80's, which made people lives becoming harder, and more students abandoned schools?

2)- What made some people become arsonist ?

3)-  Which department would get budget cut following the fire-companies ?

              All the stories that we read until now are dark and sad ones, and I can predicts the following stories won't be happy at all. However, I think that the author wants to use some heart-rending tales to give readers a message that there are still some good Detroit people who won't get contagious attitudes, and these people believe that one day Detroit will recover its vanguard.