I'm not sure this book provides the explanation promised in the subtitle, but it's a pretty good review of the housing mess that peaked and imploded in the last decade. Katz goes back to the 1930s to explain the U.S. government's role in encouraging and facilitating home ownership. When she gets to modern times, she uses case studies to humanize the hope, loss, and sleaze that played out in the housing bubble.
Cities get more attention here than in some other books that focus on sprawling subdivisions. Katz shows how unscrupulous lenders destroyed once-stable city neighborhoods. She also has a chapter on New York City's atypical housing market and its transition from rent-controlled apartments to expensive condos or co-ops.
One interesting fact that I read for the first time anywhere in Our Lot: Chicago gangs got involved in real estate flipping schemes because it was a great way to launder drug money. I wish Katz had said more about this or given a source in her endnotes.
This book is deceptively long, 228 pages that read like 350. That isn't to criticize Katz's writing; the book is just really dense and took a lot longer to read than I expected. It's a good book, but it might be more than the average person wants to read about the topic.
Katz doesn't cover the financial market aspect of the boom/bust very well, but reading Our Lot along with Matt Taibbi's Griftopia would provide a pretty good picture of what was happening on both Main Street and Wall Street.