The Gen Con event says players are expected to bring there own materials. I couldn't find instructions as to what players at Gen Con should bring, so I contacted customer support. Here is the reply:
Zach (Asmodee North America)
May 7, 14:23 CDT
Thank you for contacting us with your inquiry. All Investigator decks, chaos bags and materials are suppose to be provided by the attendees and we will be only providing the scenario itself. We ask that you bring investigator decks via the standalone rules on page 19 of the rules reference. If you have any further questions or concerns please feel free to contact us again!
Customer Service Representative email@example.com