“Not a single one of them has told me, ‘I don’t want to be here,’ ” he said in a recent interview in his office next to downtown’s Campus Martius Park, formerly among the city’s busiest gathering points and a focus of his campaign. “Kids coming out of college want that urban core excitement, more and more.”

DRESSED in a red-checked button-down shirt and a blue blazer, Mr. Gilbert is 5 feet 5 inches of restless energy. He has slicked-back dark hair, a Hollywood smile and dolorous eyes that give him the look of a man in need of sleep. Growing up in Southfield, a nearby suburb, he spent little time in the city. One of his earliest memories is of his father, who owned a nightclub-restaurant in the city, explaining the Detroit riots as the violence unfolded over five days in 1967, leaving more than 40 people dead and 2,500 stores burned or looted.

It was a searing moment in the city’s history, one that highlighted racial disparities that still haunt Detroit.

“People my age, we would hear from our parents and grandparents who were raised in Detroit about how great this city was, from 1900 to the 60s,” Mr. Gilbert said. “But none of us had any memory of that. And it wasn’t until my late 20s and early 30s, when I started traveling for business, to places like New York City and Los Angeles, that I realized how much we were missing. As I started visiting these great American cities, it hit me — man, how did we blow this so badly?”

He seems to consider it his duty to rebuild what a previous generation allowed to fall apart. He aims to turn downtown into a high-tech hub, where young entrepreneurs both live and work. (He and a handful of companies are offering rent and mortgage subsidies to people willing to live downtown.) These pioneers will have easy access to high culture: the city’s leading museum, the Detroit Institute of Arts and the Detroit Opera House are nearby, as are stadiums for the city’s professional baseball and football teams.

About 80 small companies have already settled into buildings owned by Bedrock, many of them start-ups funded by Detroit Venture Partners, a venture capital firm co-owned by Mr. Gilbert. A Twitter office is here, too, as is a branch of Uber, the online taxi-calling service. National brands, like Nike, are being courted.

A master salesman, Mr. Gilbert describes a reinvigorated downtown as though it is inevitable, but there are more than a few skeptics. They include Mr. Ryan, who teaches in the department of urban studies and planning at M.I.T.