The public rage building against Mayor Mamdani over his attacks on Gotham’s wealthy business leaders is welcome — and well deserved.

The mayor crossed a line of basic decency with his dangerous focus on high-profile individuals, such as Citadel founder and CEO Ken Griffin, effectively putting targets on their backs.

Even in purely financial terms, the socialist mayor’s “tax the rich” war cry is madness.

In an era where money is mobile and sky-high New York taxes already helped drive away hundreds of thousands of residents to Florida and elsewhere, another punitive measure would be destructive under any sane definition of the city’s well-being.

Yet here we go again with the pied-à-terre tax on luxury second homes in the five boroughs.

Supporters in the city and Albany, including Gov. Hochul, spout the incoherent claim that the tax system is “fundamentally broken,” despite knowing that high earners already pay a disproportionate amount of total taxes.

The facts didn’t stop Mamdani from doing a victory dance outside Griffin’s $238 million Manhattan penthouse and boasting that he had kept his promise to “tax the rich.”

Treating job creators, business builders, high-income families and philanthropists as public enemies is nuts.

They are the proverbial golden geese, and instead of being vilified, they should be hailed and thanked.

If they quit the city and move their families, companies, employees and personal spending to friendlier climes, the city and state would be worse off in every measurable way.

Warnings sounded

Consider philanthropy alone.

A billionaire known for his extensive gifts to the city’s top medical institutions told me that if he left New York, he would take his philanthropy with him.

Multinational investment funds of the sort that Griffin controls are economic powerhouses.

The financial services sector is responsible for as many as 10% of all private jobs in the city, according to a business group’s study, and the sector grew by 3% last year.

If that growth continues, the firms would create a projected 10,000 new jobs over the next five years and pay $8.4 billion in taxes.

The study, by the Partnership for New York City, warns that even a minor slowdown would lead to thousands of fewer jobs and the loss of millions of dollars in tax payments to the city and state.

The study reflects a welcome new attitude at the partnership, which has been passive for too long.

Even President Trump, during his first-term battle to limit federal deductions of state and local taxes, told me that no business or political leaders from New York lobbied him to change his mind.

Then-Gov. Andrew Cuomo, who vehemently opposed the measure, also complained that the partnership’s leaders refused to speak up on the issue.

Both recalled how an earlier generation of business leaders worked day and night to rally federal support so Gotham could avoid bankruptcy.

In that sense, Mamdani has provided a wake-up call.

His radical agenda and the fact that he is essentially illiterate about the city’s complex finances are a major threat to its future.

Wall Street’s credit rating agencies quickly sounded the alarm with their downgrades of city debt from stable to negative because of Mamdani’s proposed budget excesses.

If he had a penny’s worth of understanding, the new mayor would have come to his senses when Griffin said his firm would “double down” on making Miami a site for its expansion, instead of Manhattan.

“Mamdani is making it really clear: New York doesn’t welcome success,” Griffin said last week.

He also said his experience “has convinced him and his partners . . . that we want to be in a state that embraces business, embraces education, embraces personal freedom and liberty and that embraces people having an opportunity to live the American dream, a dream of earned success.”

Hochul’s flip-flop

He contrasted that with Mamdani’s vision of “distributive handouts that leave people dependent on government for their lives and their livelihoods in a way that takes away their dignity and honor.”

That’s the history of freedom vs. socialism in a nutshell.

The freedom message is not being lost on others.

Marc Rowan, head of Apollo Global Management, is looking for a second headquarters location, and is now only considering Florida and Texas, The Post reports.

So if Mamdani succeeds in his war on wealth, the harvest would be stupendous failure.

Still, critics must save some firepower for Hochul.

Without her support, the 34-year-old rookie in City Hall would just be spitting in the wind.

She ushered the pied-à-terre tax through the Legislature.

Over her nearly five years in office, Hochul has repeatedly twisted plain English to claim she’s a moderate while simultaneously raising taxes and burning through taxpayer cash at record rates.

Her weathervane habits are in full swing now as she seeks re-election.

Back in January, when Mamdani was pushing her to raise taxes on wealthy city individuals and businesses, she said, “news flash, we’re not raising taxes in the state of New York.”

That certainly sounded like a firm no, and she sang the same song in March, saying the state needs wealthy individuals to live and work here so their taxes can help fund social programs, while noting that the state’s tax base has declined.

She even foolishly suggested that wealthy New Yorkers should visit Florida, to “see who you can bring back home, because our tax base has been eroded.”

Yet she violated her pledge against tax hikes by pushing lawmakers to pass the pied-à-terre tax, which she claimed, without documentation, would raise $500 million a year for the city.

Even now, on the eve of the tax taking effect, she has no idea how it would work in the real world or how much it would actually yield.

Griffin met with her, but to no avail.

No surprise, because she aims to give the socialist boy wonder in City Hall whatever he wants, in the craven hope he will urge his fellow travelers to vote for her in November.

Bruce not gaining

So far, it’s working, politically.

Her GOP opponent, Nassau County Executive Bruce Blakeman, has not been able to capitalize on public frustration with her.

A recent Siena poll finds that Hochul’s job approval and favorability ratings each declined by 8 percentage points over the past month.

But the same survey found that she increased her lead over Blakeman to 16 points, 49%-33%, a gain of 3 points since March.

A key problem for Blakeman is that he remains a stranger to most voters.

About 64% told pollsters they never heard of him or have no opinion of his candidacy.

Yikes.