Completely wrong
These people are hard working small business owners who have opened up restaurants, bakeries, and other businesses, in particular in Dearborn which has kept it afloat
Even national review suggests providing visas for immigrants to specifically go to Detroit to help rebuild it
http://www.nationalreview.com/corner/354118/saving-detroit-through-immigration-veronique-de-rugy
The TV show depicts them as drug dealers and mafia types, the wikj-pedia article does not say how they support themselves, just that there were several hundred thousand of them brought here.