When you're the scrappy underdog, a fierce, get-out-of-the-way startup strategy can work pretty well. But once you've found more success as a company, well, this attitude can start to rub people the wrong way. Just ask Travis Kalanick.  

The Uber CEO offered this as a reason why he's been somewhat demonized over in the last couple of years as Uber has come to reach its $18.2 billion valuation. Kalanick spoke Monday in San Francisco at TechCrunch Disrupt, which drew about 3,500 attendees.

"When people start to perceive you as the big guy, you're not allowed to be scrappy fierce. If you're the little guy that's cheered, that's lauded. That's a heroic sort of startup story," Kalanick told TechCrunch Founder Michael Arrington. 

Arrington had referred to Kalanick as a "Darth Vader figure" in the startup world. Over the years there have been a series of stories about Kalanick's attitude and his company's aggressive tactics. 

For example, Kalanick has been accused of behaving immaturely when dealing with regulators in the company's earlier years.

Also, just this year Uber reportedly tried to poach drivers from Gett, a New York City competitor, by hailing rides from the company repeatedly and then canceling. "After a ride had been confirmed, and the Uber employee had access to the Gett driver's information, Uber texted the driver in an attempt to recruit him or her," Inc. reported.

Some might call it cutthroat. Kalanick describes it as being "scrappy" and "abnormally perfectionist." He explained that his approach comes from running his first startup, a networking software company, in the early 2000s. Kalanick said that he ran out of money so many times that he had to move back in with his parents.

"It requires you to be abnormally perfectionist, abnormally fierce," he said. "Because the difference of that last inch is the difference between living at mom's one more year or essentially just being poor." But Kalanick indicated that the approach doesn't work as well after your company has levelled-up. 

"You have to find different ways of communicating. And just understand that people look at you as the big guy now," he said. 

Arrington pointed out that Uber hired President Obama's former campaign manager David Plouffe to work with Uber on its image. The characteristically blunt Arrington also noted that Kalanick was a lot smoother in his interview style than he'd ever seen him before. 

Kalanick laughed and swore that it had nothing to do with Plouffe (he doesn't start until late September) or media training. 

"My [communications] team wishes I took media training. Have you seen some of the things I've said?" Kalanick joked.