How Easy Is It to Hack a Public Yfi Network?

jeff siskin meets bruce snell, the cyper security and privacy director for maccofy. The pair attempt to replicate the exact cafe y fi hack that the main character on mister robot pulled off. It's really easy, once you connect a wireless network, to sniff all the traffic that's going across it srightway. Do i have anything to be worried about? Am i being naive?