Sometime enough but sometime not and depends on your luck

RTP is just percentage that can change if we play so we can't expecting the RTP helps us to win. A slot game is difficult to get scatters but that makes people curious and want to play more and more.
Many people wants to win and chasing the big win so they willing to spends more money. I am rarely getting scatters but I don't chasing it by spending much money. If playing for some time don't gives me win, I will quit and no need to keep playing.
Popular slot games gives attraction to gamblers so they will return to play the game.
Yes, you are right, I also think the the idea of stopping whenever things are not going well is very important, because a lot of people ignore that and end up spending more than their budget. because RTP can look very attractive on paper but in reality it is not guarantee you anything in short-term.
At times, it's easy for people to get carry away, must especially when they are close to big win, that curiosity is what keep many players stuck,
And about the popular games, it good to set limit, because they are built to keep players engaged, that's why is good to set limit and not let excitement control your decision.