He's trying to root out ignorance. He believes that false beliefs are dangerous. That if you believe that a car won't kill you if you cross in front of it you're in big big trouble. And if you believe that the root of all happiness is money you're in big big trouble. So he's not really trying to lecture to people. He's not trying to tell them I know stuff and you don't. He's using the Socratic method of questioning people to make them examine themselves and their own beliefs so he can expose truth.