RTP estimates the share of stakes a game returns over a very large number of...

https://rapid-wiki.win/index.php/Do_%E2%80%9CHot%E2%80%9D_and_%E2%80%9CCold%E2%80%9D_Machines_Exist,_or_Is_That_Just_Variance%3F

RTP estimates the share of stakes a game returns over a very large number of plays; it is not a promise about one session. A 96% RTP means a 4% house edge on average over time