When I first started gambling, everyone was promoting 1% house edge dice, so I immediately learnt about house edge and later I learnt about RTP when crypto casinos added slots on their websites. I don't know if there are still players who don't know about RTP but I can say that Metawin is a huge promoter of RTP, they have slots with the guaranteed highest RTP.
Believe me, most gamblers have no idea what house edge or RTP are—they don’t even know these concepts exist. This forum (Bitcointalk) has helped many gamblers understand them, but not all gamblers visit this forum.
they have RTP and Volatility under the image of every game, so it should be intuitive for every player to click on each of them and when they click on them, a popup appears that explains what RTP and Volatility and what they mean under each game.
They won’t click on it as they won’t read the ToS (we know most users don’t).