Sudhir Venkatesh’s book Off the Books: The Underground Economy of the Urban Poor will tell you the answer.
I just finished reading it this week and while it wasn’t as engaging as his previous Gang Leader for a Day, it was informative. It profiles how “hustling” is a necessary part of life for many in the urban poor. He spent over 10 years “hanging out” on the South side of Chicago and got to know many of the people who lived there. He takes the experiences of prostitutes, drug dealers, ministers, auto mechanics, the homeless and petty thieves and weaves an interesting tale of how marginalized people use their entrepreneurial skill to survive.
While it can be dry and times, and Venkatesh seems to repeat himself in some of the chapters, the book is worth reading. If you haven’t read Gang Leader for a Day, I would suggest reading it first, as its a much better intro into Venkatesh’s work than Off the Books.
You have to admire the entrepreneurial spirit that many of people in the book display. The traits that many of the “hustlers” have are the exact traits that many startups are looking for: innovation, willingness to change business models quickly and operating without significant cash. It would be great if there were a way to harness their willingness to take risks and come up with solutions on the fly in other, more productive ways that would allow the marginalized hustlers to live a better life.