People love to talk about themselves, they like to share what they know. If you just ask them to.
Questions are a great way to learn. Both to know more about the person you are talking with and the things they know about. It's a good opportunity that shouldn't be missed. Listening to them makes them also value you more as you show appreciation towards them.
The problem is, we love to talk about ourself so much we often forget the other person. We don't ask those questions, we just keep answering the ones they are presenting to us. And we feel good about it.