But Mr. Hsieh had a vision. In the same way that Holacracy might get Zappos employees collaborating again, injecting bodies and businesses might revitalize a blighted neighborhood. Mr. Hsieh also had $350 million of his own money to spend on the idea.

While moving the company, Mr. Hsieh also founded the Downtown Project, allocating $200 million to buy about 60 acres of real estate. The remaining money was split into thirds, $50 million each for small-business investments, venture capital stakes in technology companies and support for education and the arts.

By 2013, new life was coursing through downtown. A few upscale restaurants sprang up. Then came a complex constructed out of shipping containers that is home to a salon, a bar, a toy store and a candy shop. Now there is an independent bookstore, a gourmet doughnut shop, a vegan restaurant, a sushi bar and a yoga studio. Foot traffic is up, and crime is down. Last year, Mr. Hsieh gave up his sprawling condominium on the 23rd floor of a luxury apartment building and moved into the trailer park.

Mark Guadagnoli, a kinesiology professor of the University of Nevada, Las Vegas, who also specializes in optimizing performance and communication in the workplace, has lived in the city for 20 years. “When I moved here, I would go downtown and be uncomfortable. Then it got worse and worse,” he said. “Now it’s a really fun place to go. It’s a destination. Anyone who says the Downtown Project has not made a significant and lasting impact on Las Vegas is crazy.”

Still, change in downtown Las Vegas is slow going. Homelessness remains endemic. Quality housing is in short supply. As a result, many Zappos employees are still living in the suburbs and commuting to work. Building street life in a city where the temperature routinely hits 100 degrees has its challenges. Shops and restaurants catering to a new creative class have opened, but few are brimming with business. Many are hemorrhaging money. Some, including a co-working space and a flower shop, have closed.

As for the start-ups funded by Mr. Hsieh — who personally lured many entrepreneurs to Las Vegas with pitches about starting a Silicon Valley in the desert — a few seem to be doing well, but several have shut down. And in a devastating blow to the community, three entrepreneurs funded by the Downtown Project committed suicide from January 2013 to May 2014.