A tidy sum, as it turns out. According to Christie’s, this canvas alone could fetch up to $200 million. Once interest rates return to normal levels — say, 6 percent — the forgone interest on that amount would be approximately $12 million a year.

If we assume that the museum would be open 2,000 hours a year, and ignore the cost of gallery space and other indirect expenses, the cost of keeping the painting on display would be more than $6,000 an hour. Assuming that an average of five people would view it per hour, all year long, it would still cost more than $1,200 an hour to provide the experience for each visitor.

Notwithstanding the crudeness of these approximations, we can say that even a very wealthy taxpayer would be reluctant to pay anything close to $1,200 an hour for the privilege of viewing this painting. And that suggests that most taxpayers think the same money could deliver much greater value if spent in other ways. Of course, the painting might still justify its cost if other indirect benefits were large enough.

Yet the point remains that prices affect the options we face. Relative to famous art, lesser-known works have become much cheaper in recent years, despite no evidence of any decline in their quality. In a rational world, this change would encourage curators to invest more heavily in emerging artists.

Many of these artists produce works that are deeply affecting, yet surprisingly affordable. Talented curators could assemble collections of their art that would delight visitors and draw fulsome praise from critics. And as those works became better known, their value would climb rapidly.

Ownership by public or nonprofit institutions is also not a prerequisite for public exhibition of prized art. The superrich pay so much for these works largely because they are already so famous. Yet being chosen for prominent display in public spaces was how many of these works became famous in the first place. If fewer museums owned them, the rich would have good reason to lend them more often for public display, as indeed many already do, thus preserving and enhancing their value. If sold, many of the institute’s famous works would return as loaners, along with such works from other collections.

If billionaires choose to bid up the prices of trophy art, that’s their privilege. And because most of them will die with large fortunes unspent, they can buy what they want without having to buy less of other things they value. But because money for worthy public purposes is chronically in short supply, city officials and true philanthropists must grapple with agonizing trade-offs.

Yes, communities benefit from famous paintings, but they also benefit from safer roads and better schools.