As a high-earning money manager — including for the Soros Fund — Howard Rubin seemed to have it all. There was the multi-million-dollar co-op on the Upper East Side, as well as a $9 million waterfront estate in the Hamptons. Rubin and his wife, Mary, were known for their generosity on the city’s philanthropy circuit; from 2015 to 2016, the couple gave nearly $500,000 to charitable causes, including the New York Junior League and Hope for a Cure. But there was one other real-estate holding he kept hidden: a luxurious Madison Avenue penthouse, outfitted with blow-up photos of Playboy models...