RTP is a long-run average; the house edge is the casino’s mathematical share:...

https://touch-wiki.win/index.php/How_Do_I_Pick_a_Slot_If_I_Only_Care_About_a_Big_Hit%3F

RTP is a long-run average; the house edge is the casino’s mathematical share: 96% RTP = 4% house edge. Volatility affects how wins and losses arrive. In a short session, results can differ sharply from the average—there’s no guaranteed return.