I'd be inclined to take the Socratic method: "Why don't you like Bitcoin? Where did you hear that Bitcoin users have been doing X, Y and Z? What makes you think that banks (or Paypal or Western Union) are better? If you found evidence to the contrary, would you change your mind?"
If they don't know what the hell bitcoin is then your question doesn't make any sense if they have never heard about bitcoins then there is no point in asking them why they don't like bitcoins and why they prefer paypal or wu i hope you are getting my point.