Taking in the spectacle from his ninth-floor office, Dan Gilbert was among those cheering loudest. The billionaire cofounder and chairman of Rocket Mortgage had helped clinch the event with a personal phone call to his friend NFL commissioner Roger Goodell, and seeing it unfold felt like the culmination of a dream.

“As you grow up and start going to other cities, people start making fun of Detroit,” Gilbert says from that same office on a sunny March afternoon. “It always stuck with me as something I didn’t like. And I always said if I could make an impact or change that, I would.”

Gilbert has done just that. The billionaire has garnered plenty of attention over the years for using his numerous businesses—which span industries from property management to venture capital to entertainment—to boost the image of his native Detroit and that of Cleveland, its Midwestern neighbor and home to the NBA team he owns.

What is far less known is how Gilbert also relies on a very different business operation as a secret weapon to advance both his own fortune and those of the cities he loves. Specifically, Gilbert has shrewdly deployed his family office, the private wealth management company for his personal fortune, which currently sits at $27.8 billion. In doing so, he joins a fast-growing new class of billionaires who are using family offices for strategic purposes that go well beyond the financial well-being of their immediate clans and are remaking entire industries—and even cities—in the process.

Explosive growth

Spend any time with Gilbert at Rocket’s offices at One Campus Martius, or OCM, and you are bound to hear one of the aphorisms he is fond of drilling into his 20,000 employees: “Every client. Every time. No exceptions. No excuses” is one of his favorites, as is “Numbers and money follow; they do not lead.” Devotees of Gilbert’s so-called isms can even pick up a bound, printed book full of them at OCM, which houses not only Rocket Mortgage, but several of Gilbert’s other ventures, including StockX, an online marketplace. You’ll find that office just past the basketball court on the 10th floor.

Explore OCM a little further, and down a set of winding stairs is Gilbert’s family office—named Rock in a nod to his biggest company—with its 70 employees. When addressing this group, Gilbert is likely to impart yet another ism: “For more than profit.” The saying reflects how, unlike other family offices that are focused exclusively on expanding the wealth of those who establish them, Gilbert’s aspires to take a different tack. By investing directly in Detroit and Cleveland, the billionaire hopes to deliver long-term benefits to his businesses, say, by making the cities more attractive to college-educated workers, or by bringing in more tourism dollars and furthering a virtuous cycle of homegrown prosperity.

Real estate is Gilbert’s bread and butter, but his other primary investment interest is startups, which he funds via his venture firm, Detroit Venture Partners, and oversees using the family office. The office’s startup portfolio includes Detroit-based e-bike manufacturer Bloom and trendy furniture brand Floyd. But all of his companies make strategic plays. In early March, Rocket Companies announced it would acquire real estate brokerage Redfin for $1.75 billion.

Of course, Rock also serves more pedestrian purposes, such as providing a central hub to keep tabs on all the entities Gilbert owns. The family office employees understand what each company does and help facilitate connections between them to accomplish Gilbert’s goals.

Gilbert’s family office is unusual for many reasons, not least its very public physical presence in an office building and its decision to let a reporter into its midst. Most family offices prize discretion, operating in near-total secrecy as they execute the sensitive financial tasks of billion-dollar dynasties, including tailored advice for charitable giving, investments, succession planning, tax planning, and settling intra-family financial and business disputes. Often, they also help manage the family’s multiple luxury homes, private aircraft, and yachts.

But these offices come in all stripes, and are as unique as each of their founders and the families they serve.

“If you’ve seen one family office, you’ve seen one family office,” says Charles Wilson, senior vice president of investment management at Selby Jennings, a financial services recruiting firm. “They have so much latitude, absolutely no restrictions. They’ll run a lot of things a lot of different ways.”

As the wealth of the world’s richest has climbed in recent years, so has the number of family offices: There are an estimated 8,000 single-family offices worldwide managing more than $3 trillion in assets, a dramatic jump from the approximately 6,100 that existed in 2019, according to a 2024 Deloitte report. The total number of firms is expected to balloon by 75% by 2030, per Deloitte, with the total wealth of the dynasties behind these private companies expected to grow to $9.5 trillion.

Family offices like Gilbert’s have also become a major force in wealth management, leading venture capital firms and high-profile private companies to compete for their capital, rather than relying on banks or other institutions. Their influence in the investment community is expected to only grow in the coming years.

This is illustrated in a PwC report that found family offices supplied nearly a third of startup capital worldwide in 2022. In the past year, buzzy startups like Perplexity AI have received direct investments from the likes of Bezos Expeditions, the single-family office of Amazon billionaire Jeff Bezos. Gilbert’s, too, invests in startups founded by employees of his other companies. All this underscores how family offices have grown so substantially in recent years that they have become a major sector in their own right, with VC firms, private equity interests, and private companies all vying for access to them.

Creating a lasting dynasty

Each family office pursues its own distinct investment strategy. In the case of Gilbert’s Rock, that includes putting the almost $30 billion at his disposal toward what he views as Detroit’s most pressing issues. So far, that’s included investments as varied as the 2024 NFL Draft—where the city’s Lions invested in their own future by choosing a promising Alabama cornerback for their top pick—as well as paying off $15 million in property tax debt to reduce the city’s infamous housing blight, and renovating historic buildings downtown to attract new tenants.

Aside from investing and tax management, a major function of any family office is legacy planning. Many are focused not just on asset accumulation, but on preservation, and they go to great lengths to prepare the next generation to inherit their family’s wealth.

“The smartest families aren’t just passing down wealth, they’re passing down values,” says Bruce K. Lee, founder and CEO of Keebeck Wealth Management, a multifamily office. “When you include [the next generation] while the patriarch is still alive, they learn to see the capital as their own.”

In that regard, Gilbert’s office is more typical. Eldest son Grant, 27, keeps an office in OCM and runs a number of his own ventures in concert with his family. He says his parents instilled the values of hard work and community pride in himself and his siblings from a young age, which influences the work they all do.

Gilbert hopes to inspire not just his own children to do good work, but the next generation of family offices as well; emissaries from other ones visit Rock and OCM to see how they can implement the strategies that have worked in Detroit in their own hometowns.

Of course, Gilbert and his dealings in Detroit are not without critics. His companies have benefited from controversial lucrative tax breaks and are concentrated in just a few square miles of the city’s expansive limits. Some question why a single private citizen seems to have just as much—if not more—input on what happens in the city as the local government. Still, his recent efforts have made him a hometown hero for many Detroiters—his company’s move to OCM is seen by many as the spark that helped ignite the city’s 21st century renaissance.

Gilbert and his family office employees stress that their efforts are far from purely philanthropic. With their businesses and real estate holdings aplenty, they all stand to benefit handsomely from Detroit’s rebirth. Even the “For more than profit” philosophy is meant to attract younger talent who want to feel like they are contributing to the greater good, Gilbert says.

But he’ll know his work is done when downtown Detroit is as bustling as he remembers it being when, as a teenager, he visited the bar his father owned there. Maybe not 750,000 people crowded into Campus Martius bustling, but storefronts filled and happy hours well attended.

“We built all this wealth over a period of 40 years, and now it’s time to deploy it,” Gilbert says. “I want to be alive when we deploy it, that’s for sure, and to see the impact in my own hometown.”