I guess slot now has increase the number of the fan because young generation like to playing slot game using their smartphone. They don't have to learn specific skills to play slot game and only need to know how to deposit and withdraw and then start playing. Moreover, slot games has many providers that giving different experience and the reward is also different. That makes many people choose one by one of the slot game from many providers because they think that they will get their luck. More young generation know and play this slot game instead the other gambling games because this game is easy to play. We may see the increasingly of the gambling addiction which can happen in the young generation if they don't know how to stop.
But I think that young generation prefer to play game where an object flies up and you have jump out, stop until it crashes of explodes. Usually such games have Crash, Flight, Rocket and etc names. I think they are more popular than slots. There are huge variety of slots games, but this games does not have all-in button. With s desire to get expensive things as quick as possible, young generation would play instead Crash/Flight/Rocket/etc because they are impatient and want to get everything with little effort. I think it depends from location, but when I see gambling ads that arent promoting casino in general, I see those Crash/Fligh/Rocket game videos most of the time.