The reason why slot players prefer to keep on playing the same game most of the time and rarely to try new game is because they know the game well.
Although we know that there is no pattern that will help players to win but once we played the game a lot, we may have a bit clue on what is going to do.
Of course luck will always be the main thing, although we have a clue or a feeling but it wont be as what we feel/predict.
But I'm sure most slot players like to try new games because they must be interested to try because maybe new feature or new things.
Playing a same game that they are familiar with will help them reducing risk of loss, increasing chance of win and as gamblers, I believe none gamblers want to lose money. So playing familiar and most favorite games is their most popular gambling choice by both reasons.
Sometimes gamblers can try new games for entertainment and exploration but it won't last too long if they feel uncomfortable and see new games are too risky for their gambling capital. When they feel like that, they will return to their most favorite and familiar games again. It's natural instinct from gamblers to survive in this risky entertain industry and to defend their money as most as possible.