It is really hard to get people to open up about their interests. People with interests are so used to being shut down by other people "yeah that is interesting now let's talk more about me" that you need to slowly coax them out. The best way is to listen intently and ask probing questions to draw them out. Once they feel safe you will have some amazing conversations.

Just watch out for the bores that will just parrot whatever they heard on FOX/CNN last night.