MARK PENN: Socialist Mamdani sold a tax on billionaires. Regulars homeowners could pay the price

It sounded simple and even kind of warmly populist in nature — a small tax on "pied-à-terre" properties in New York City. But the more you dig into it, as with all things from Mayor Zohran Mamdani , the more you see it as part of a far more devious plan that could destabilize the New York City housing market and cost middle-class people their homes and savings. Gotta love whoever pulled this French name into implying the tax would just fall on a few very rich people — no more than 31,000. That w