There’s been plenty of outrage directed at Goldman Sachs lately, and a common complaint is that the Wall Street firm is earning huge profits by making risky trading bets even as it enjoys government guarantees, either explicit or implicit.But Robert Lenzer, a national editor at Forbes magazine who worked at Goldman during the 1960s, argues that Goldman is no reckless gambler. In fact, he says, a look at the firm’s positions in credit default swaps — the derivative that nearly toppled American In