The reason why you see these tournaments all over online casinos is because they are trying as hard as they can to promote them. Their marketing strategy for these tournaments are very aggressive because they are very profitable for the casinos and the players.

Players that are new to online casinos won't have to wager a very big amount but in exchange they can get a chance to win a very big amount of money if they reach the final rounds.

For the online casino side, it assures them that there will be a few thousand players, even though they will wager a much smaller amount of money, the online casino is assured that they will play and that there can be only 1 winner so the profitable margin is very high for the online casino as well.