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

https://www.novabookmarks.win/rtp-estimates-returns-over-many-plays-96-rtp-4-house-edge-not-a-promise

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.