We may not want to admit it (even to ourselves), but talking about ourselves gives us a "high." About 40% of everyday speech is devoted to telling others about what we feel or think, because it triggers the same parts of the brain as food and money. This is one of the secrets of being popular: Ask other people questions about themselves.
In the May 7th edition of the Wall Street Journal, Robert Lee Hotz quotes neuroscientist Diana Tamir as saying, "Self-disclosure is extra rewarding. People (are) even willing to forgo money in order to talk about themselves."