RTP estimates a game’s long-run return: 96% RTP means a 4% house edge....

https://wiki-zine.win/index.php/Why_the_Investing_Analogy_Breaks_Down_for_Casino_Games

RTP estimates a game’s long-run return: 96% RTP means a 4% house edge. Volatility affects how often results swing up or down. In a short session, outcomes can differ sharply from the average, so a game’s RTP doesn’t predict what you’ll get back.