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.…