White people over the decades have invented many sneaky, devious methods for leeching away any wealth that black people (and other minority groups, but mostly black people) manage to accrue. Contract housing in Chicago and Detroit was one of the harshest and most damaging ways to do this.
It was a scam where black home buyers were tricked into buying a house where the price was never actually known. "You own it when I feel you've paid enough," was the basic gist. And a single missed payment meant eviction and a total loss of all equity accumulated.
I read once that in Detroit in the 1950s and early 1960s, homes were flipped every 18 months by unscrupulous white real estate agents to black families who just wanted a piece of the American Dream.
The Ghetto Is Public Policy - Ta-Nehisi Coates - The Atlantic
I spent the last week interviewing men and women, and the children of men and women, who bought their homes on contract in Chicago during the 1950s. Contract buying sprang up in Chicago after the federal government effectively refused to insure mortgages for the vast majority of black homeowners, even as it was insuring the mortgages of white homeowners, and encouraged banks to redline black and integrated neighborhoods. The import of mid-20th century housing policy -- along with private actions (riots, block-busting, contract lending, covenants) -- has been devastating for African Americans.
Buying on contract meant that you made a down-payment to a speculator. The speculator kept the deed and only turned it over to you after you'd paid the full value of the house -- a value determined by the speculator. In the meantime, you were responsible for monthly payments, keeping the house up, and taking care of any problems springing from inspection. If you missed one payment, the speculator could move to evict you and keep all the payments you'd made. Building up equity was impossible, unless -- through some Herculean effort -- you managed to pay off the entire contract. Very few people did this. The system was set up to keep them from doing it, and allow speculators to get rich through a cycle of evicting and flipping.