Because dice in my opinion is the easiest game to play. As well as this game has long played. Thus, gamblers are familiar with gambling types of dice.
Even if your not familiar with this game also you can start playing within a couple of minutes because it is so easy to play and that's why it has become so popular game for online casinos. I also started online gambling with dice game apart from cricket betting.
well even beginners can start doing it without any hard thing to understand dice already conquer the taste of real gamblers, those who are in the side of gambling for a daily routine they think that gambling can easily be done and they can win in an instant just like what OP thinks about this activity, but in reality dice is the easiest game to burned your bankroll in the long run.
Whether it is a dice game or any other game in gambling the end result will be losses if you play long. Not only in dice game people will lose money so you should need to go to gambling or playing dice game only if you want to spend your free time to get fun but not to make money.