Photo-Illustration: Curbed; Photo: Stan Honda/AFP via Getty Images For years, buying an apartment at 740 Park meant something. And that something was, quite simply, that you’d won. It was not a building for those on the make; it was a building for those who’d made it, the socially and financially dominant. The childhood home of Jackie Kennedy Onassis (her grandfather built the place in 1929), 740 Park counted John D. Rockefeller Jr., a Chrysler heiress, and numerous financiers among its first residents. In the boom periods of the 1980s, 1990s, and early 2000s, apartments routinely fetched record prices, sometimes provoking bidding wars between billionaires. In 2000, Blackstone founder Stephen Schwarzman…