Gambling is not entirely based on luck. It is entirely based on luck for those who have no previous experience and place their bets on the chest. Every game has some tricks if you get good experience with that game and know how to play that game properly then you will understand many tricks to win in that game. And you can win more than new gamblers in the same game. So in this case it can be said that gambling does not depend entirely on luck but some aspects also depend on one's own experience. But since I don't use gambling as a profession and am not interested in doing it, I don't develop gambling games myself.
Could you please explain to me what factor besides luck can be used in these games?
If you are referring to bankroll control, then I agree with you because increasing or decreasing your bets according to the bad luck/luck of the moment is indeed important, but in a game where the next result is completely unpredictable (unrelated to any external factor) it is impossible to predict the next result or say that the probability of "A" is greater than that of "B".
This scenario changes, for example, if you are betting on a card game, such as poker, where it is possible to calculate the probabilities of the next play based on the cards that have already been turned over so far.
But in a slot machine or a dice game, where the probability of the next bet is the same as the previous one, it is impossible to predict and create a strategy.