Bill Ackman’s about-face on Andrew Cuomo is just the latest example of how even great businessmen can’t instantly succeed when they set out to influence politics.

Immediately after a fumbling Cuomo lost the Democratic mayoral primary to far-left upstart Zohran Mamdani, Ackman publicly promised to bigfoot the process and save New York by “crowdsourcing” to find the “best centrist candidate” to take on the Democratic Socialists “on the campaign trail and on the debate stage.”

“I will take care of the fundraising,” Ackman vowed. “There are hundreds of millions of dollars” to be tapped quickly.

Oops: After a few days of poking around under the hood and reading the manual of local politics, Ackman realized that taking over City Hall isn’t just a matter of holding a candidate cattle call and calling up a few buddies to ante up millions. 

It’s actually a lot more complicated.

So Ackman backed off on finding a savior to parachute into the muddle and called for Cuomo to drop out: The ex-guv’s “subdued energy” and failure to win a gimme election, he explained, showed “that he is not up for the fight.”

Instead, Ackman declared, he was 10 toes down for Mayor Eric Adams, “who is ready to go to battle, guns blazing with enormous energy and clarity.”

Two two months later, Adams still lags in the polls and seems poised to exit (perhaps to join the Trump administration) — so Ackman is back on Team Andy, calling Cuomo an “experienced leader” who has the “relevant experience and skills” to lead us.

Faint praise never won fair city.

We don’t mean to be too tough on Ackman: After all, it’s practically yesterday that he started paying much attention to politics of any kind, and he’s scored some real points in other battles.

Extremely successful people, who’d never invest big in an industry they don’t remotely understand, nonetheless time and again treat politics as if it’s an easy game.

You may sincerely mean to save New York from the error of its ways, but then it turns out that other people, perhaps not as rich but just as smart, got there first.

Folks on the left may be dead wrong about their policies, but they understand that politics is a matter of organized, sustained effort, the cultivation of critical constituencies and year after year of consistent base-building.

You can’t summon up decent candidates from nowhere, either: Even the best free agents come up through somebody’s farm system.

New York City politics, in particular, is a rat’s nest of competing ethnic blocs, labor unions, activist groups, varied business interest small and large (and politically wise and naive), as well as a thicket of election law that was built to stymie high-minded outsiders like Ackman.

If sober-minded centrists and advocates for normal people want to retake New York, they need to commit for a much longer haul.