Travis Kalanick on the founder's paradox: the better you get, the harder it is to stay fired up. "The young entrepreneurs that are coming up right now don't totally get it." "When you get into your 3rd and 4th company, I don't know, this may be even my 5th at this point, you get fricking really good at doing stuff." "Things that used to take me a day or three days, a lot of stress, anxiety, like, 'How am I gonna do this?' take me like 45 minutes. And that's a beautiful thing." "I'm so used…