Then, there is her take on retirement. Her father had $75,000 to lend to her because he had been forced to liquidate a once-thriving business that he built after the family’s earlier lean years. “I never grew up with any idea that there would be retirement,” she said. “You were trying not to go to a payday lender. My dad’s retirement was supposed to be the business.”

Ms. Haimerl is a writer and Mr. Kaebnick is a computer programmer, and perhaps they can work well into their 70s or 80s. In the meantime, their net worth is negative. They did get a mortgage after the work was done, and the appraiser assigned the $300,000 value to their home, a triumph in their neighborhood at the time.

They pulled most of that money out in a mortgage to repay many of their other debts and write a giant check to their contractor, Calvin Garfield. They still owe him about $80,000, but aspiring Detroit residents should not expect loose terms if they come to town.

“I’m confident other contractors would not have made the same call,” Mr. Garfield said. “But I do think everyone we have done business with has become a friend, and in that mix of things, this seemed to be the right thing to do.”

The couple desperately wants to repay him, and because their income is just over $100,000, they expect to do so sooner rather than later. Ms. Haimerl freelances, and they have an Airbnb side business going using some of that 3,000 square feet. For just $65 a night, aspiring Detroit residents can soak up plenty of sober-minded advice and bear witness to the kind of house that a lot of money and worry can buy.

But how best to explain away their lack of retirement savings? Plenty of people who sank their life savings into real estate in less desirable parts of Brooklyn or San Francisco a decade or two ago are probably thrilled.

So is that how they think about the money they have put into their Detroit dream? That they bet on a city instead of a bunch of stocks? “We have gotten gun-shy about talking that way,” Ms. Haimerl said. “People here say, ‘How dare you treat our city like an investment.’”