Who's the Expert?

It seems like everywhere you turn, there's someone to give you advice about something. You've got books, DVDs and speakers offering tips on How to be a Millionaire, How to land a man, How to be a Mack, etc.  But what makes someone an expert? How does a comedian who has a failed marriage under his belt become the Messiah for women wondering why they can't just get it right with men?  Ministers are men of God who deliver the word but at the end of the day, they are still men so it's interesting to see people hang on so closely to their every word.  Is it a certain title, number of degrees?  Or is it a matter of experience or can someone with enough respect and charisma to have followers become an expert?