Facebook CEO Mark Zuckerberg has evolved dramatically as a leader since his early days as the "boy-man" boss, insiders say. Zuckerberg was in the right place at the right time, but he succeeded by combining ruthless business instincts with a willingness to find leadership mentors and learn the skills he needed to run a global company. "Was he lucky? Of course. ... But you also make your own luck. The world has overlooked how great Mark is as a CEO," one early Facebook co-worker says.