John Matheson, a home inspector in Alameda, Calif., kept busy during the pandemic when the housing market was red hot. But as interest rates started to rise about halfway through 2022, he noticed that his workload began to drop. Last year, the number of jobs plummeted.

“My business is about 50 percent of what it was,” said Mr. Matheson, who works as a contractor for BPG Inspections, which provides services to home buyers across the nation. “As far as I’m concerned, it’s a really bad year.”

So bad, in fact, that “I am actually thinking about side hustles,” he said, adding that he is studying to receive a commercial captain’s license in the hope of getting a job operating a ferry or another vessel if the housing market does not rebound.

High home prices and elevated mortgage rates, which squeezed the housing market last year, have dragged down a number of other related sectors, like real estate services and mortgage lending. But housing is such a crucial cog in the American economy that its slowdown has also threatened industries like home improvement and storage.