Steven Mandis was working on a book about whether Goldman Sachs Group Inc. put profit above principles when he hit upon a new way to make money. The former Goldman Sachs banker decided two years ago to get into lending money to struggling small businesses, a niche on Wall Street where brokers offer loans with interest rates that can climb past 100 percent to dentists with bad credit and pizzeria owners behind on their bills. To some, it’s the new face of subprime…In “What Happened to Goldman Sachs,” Mandis described how the firm adopted a legalistic approach that enabled it to make more money. Unlike Greg Smith, the Goldman Sachs banker who quit in 2012 and wrote a New York Times editorial calling the firm toxic, Mandis said he isn’t blaming anyone for what he calls a slow cultural drift. “Of course, the sense that one is doing God’s work or serving a higher purpose can easily transmute into a holier-than-thou attitude and an excuse for any behavior,” he wrote in the book.