Earlier this month, Eric Richard was in Bali, Indonesia, enjoying the tropical weather and carefree life of a retiree. Last summer, at 29, Mr. Richard had quit his job as a corporate operations manager to become a “digital nomad.”

Now he is hunkered down at his parents’ house in Michigan, having returned to the United States as concerns over the coronavirus outbreak grew and travel bans were put in place around the world. He is in self-isolation as a precaution. And in recent weeks, he said, he has seen his net worth drop by more than $100,000.

“It’s definitely not a great feeling, to say the least,” Mr. Richard said.

He is an adherent of the FIRE movement, the personal finance strategy popular among millennials. It stands for “financial independence, retire early.”

The FIRE movement was born during the stock market’s historic 11-year-long wealth-creating run. Professionals in their 30s and 40s were saving up million-dollar nest eggs and quitting their jobs in the prime of life to live off investments. It was unheard-of in modern times, at least for anyone without a trust fund.