At one point, Michael Arrington, the founder of Techcrunch, asked Kalanick how he felt about being compared to Darth Vader. "I'm a Star Wars fan," Kalanick replied, "but that's a little intense." He went on to describe the six years he spent in the startup trenches with his previous company, an enterprise software maker that he ultimately sold for millions, saying that success requires a certain amount pugnaciousness. "When you're scrapping that hard, it requires you to be abnormally perfectionist, abnormally fierce."

But that same spirit that serves an underdog so well becomes a liability when perceptions of a company change. A pit bull isn't very sympathetic when it becomes the alpha. And these days, with its billion-dollar war chest and a presence in 200 cities, Uber looks like a top dog as it seeks to remake the way people hail cars and pay for rides.