RTP is a long-run average; the house edge is the casino’s expected share: 96%...

https://www.generate-bookmark.win/rtp-estimates-returns-over-time-96-rtp-means-a-4-house-edge-volatility

RTP is a long-run average; the house edge is the casino’s expected 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.