Sprint’s costly $15.5 billion gamble on Apple’s iPhone won’t pay off until 2015, according to CEO Dan Hesse. At that time, however, the iPhone will be “quite profitable,” and the company is “very happy” with the deal despite conflicting reports, AllThingsD said. Hesse sees the iPhone as a long-term investment that will slow subscriber defections and attract new customers. “We believe in the long term,” the CEO said. “And over time we will make more money on iPhone customers than we will on other customers.” Sprint sold 1.5 million iPhones in the first quarter of 2012, and while the number doesn’t approach AT&T or Verizon’s sales, 44% of Sprint’s iPhone sales were made to new customers.