With the recent opening of its sleek new quarters, the Museum of Modern Art has solidified its position as one of the world’s leading showcases for high culture. Designed by the “starchitect” firm of Diller Scofidio + Renfro, the renovation cost $450 million; that comes on top of the $425 million the museum spent on an earlier makeover, in 2004. That redesign came under sharp criticism, and within a decade a new overhaul was deemed necessary. In less than 20 years, MoMA has spent almost a billion dollars reinventing itself.

Most of that money has come from the museum’s board of trustees. For the 2004 renovation, 50 trustees donated $5 million each. For this go-round, board members have again opened their wallets, along with David Geffen, who does not sit on the board but provided a whopping $100 million. The vast fortunes that make such do-overs possible raise questions about the composition of MoMA’s board at a time when such boards in general face growing scrutiny.

Earlier this year, both the Metropolitan and Guggenheim museums announced they would no longer accept donations from those members of the Sackler family linked to OxyContin, the powerful painkiller implicated in the opioid crisis. In July, Warren Kanders resigned as a vice chairman of the Whitney Museum after weeks of protests directed at his ownership of a company that manufactures tear gas canisters that had been used against migrants on the United States-Mexico border. And on Oct. 18 — three days before MoMA’s reopening — more than 100 activists picketed an exclusive preview party, calling on one of its board members, Laurence Fink, and his company, BlackRock, to divest its holdings in private prison companies.

Individual cases like these reflect a more fundamental reality about museums: their dominance by the superrich in an age of mounting anger over income inequality.

MoMA is a prime example. Of its 51 trustees who have a vote, at least 45 (by my count) work in finance, the corporate world, real estate or law, or are the heirs or spouses of the superrich. Only a handful come from outside these gilded ranks, among them the writer and actress Anna Deavere Smith and the Harvard professor of history and race Khalil Gibran Muhammad. As has been widely reported, both MoMA and the Met expect wealthy newcomers to give millions of dollars as the price of membership. (Because donations to museums are for the most part tax-deductible, the giving is leavened with a sizable dose of self-interest.)

Art has always depended on wealthy patrons; see the Medicis, Frick and Morgan. In contrast to Europe, where museums receive significant (though now decreasing) state funding, most American museums rely heavily on private donors. And, since the late 1990s, when MoMA’s current push to expand began, its trustees appear to have been chosen overwhelmingly for their wealth, and the board now reads like a roll call of the 0.01 percent.

Ronnie Heyman, the president of the board of trustees of the Museum of Modern Art.Credit...Dolly Faibyshev for The New York Times

To take a random sample: MoMA’s president, Ronnie Heyman, is the chairwoman of GAF, a roofing manufacturer that her husband, Samuel Heyman, acquired in a hostile takeover. Philip Niarchos is heir to the fortune of the Greek shipping magnate Stavros Niarchos. Jerry Speyer is the chairman and a founding partner of Tishman Speyer, the real estate colossus that owns Rockefeller Center. Marlene Hess is the daughter of Leon Hess, the oil tycoon who owned the New York Jets. John Elkann is heir to Italy’s Agnelli family, Joel Ehrenkranz is a senior partner in a wealth management firm and Zhang Xin is a Chinese billionaire businesswoman.

Glenn Lowry has been director of the Museum of Modern Art since 1995.Credit...Amy Lombard for The New York Times

Among the biggest losers in the current system are artists themselves. With art now considered an asset class similar to equities and commodities, collectors are forever on the lookout for rising stars whose work can be bought at bargain prices and then resold for many multiples as their reputation soars. When the market moves on, careers are often shattered (except in the case of a few ever-in-demand stars).

And even those artists who do remain popular usually benefit only from the initial sale of their work; as its value appreciates, the profits go mainly to collectors and auction houses. Museum trustees have ready access to curators and gallery owners who can point out emerging artists whose work they can buy at an early stage and benefit as the demand for it grows. And with so many rich people collecting contemporary art, and the public’s interest in such art growing, museums often seek to devote more space to it to keep donors interested and openhanded.

The Metropolitan, for one, has paid dearly for such expansionism. In 2011, the museum, in a push to accommodate more modern and contemporary art, agreed to an eight-year lease on the longtime Madison Avenue home of the Whitney, which the Whitney was abandoning for its new Renzo Piano-designed palace downtown.

Perhaps the most serious concern about baronial boards is the possible constraints they place on what museums can exhibit.

The Met had to spend $13 million to renovate the building and $18 million a year to run it, contributing to a $10 million deficit. The museum was forced to shed around 100 employees, cut benefits for curators and conservators, reduce its number of annual shows and suspend a planned $600 million renovation of its modern and contemporary wing. The Met also decided, for the first time in a half-century, to impose a mandatory admission fee on all out-of-state visitors.

In September 2018, the museum finally managed to rid itself of this millstone by announcing that the Frick Collection would take over the former Whitney building. Another casualty of the mess: Thomas Campbell, the museum’s director, who was forced to resign.

Perhaps the most serious concern raised about baronial boards is the possible constraints they place on what museums can exhibit.

With its more than 40,000 square feet in added gallery space, the Modern is seeking to upend hierarchies, remake the canon and break from its longstanding white, male, Eurocentric orientation. On a recent visit to the museum, I saw many dazzling and socially engaged works, such as Jacob Lawrence’s epic series on the great African-American migration from South to North, Michael Armitage’s paintings of African despair, and Janet Cardiff and George Bures Miller’s chilling “The Killing Machine.” In one of many edgy juxtapositions praised by reviewers, the museum has placed Picasso’s “Les Demoiselles d’Avignon,” with its primitivist figures of five women of the street, close by Faith Ringgold’s “American People Series #20: Die,” a frenzied tableau of a blood-soaked race riot.