Musk laughed when told about Jeff Bezos’s timeline for engine development. “Bezos is not great at engineering, to be frank,” he said. “So the thing is, my ability to tell if someone is a good engineer or not is very good. And then I am very good at optimizing the engineering efficiency of a team. I’m generally supergood at engineering, personally. Most of the design decisions are mine, good or bad.” Boastful? Maybe. But SpaceX built and tested its first rocket engine in less than three years with Musk leading the way.