Gamblers must remember that casinos only earn a small amount of money out of the wagered amount and depending on the games they play this amount can vary and this affects the size of their bonus, if a gambler was playing a game with only a 2% house edge and they wagered 1000 the casino on average just earned 20 dollars, so when you think about it the casino cannot really afford to give a huge bonus to that player as they are barely profiting from them.
In reality that's not what happened.
Any casino doesn't have such profit calculation and if you say the casino only makes a small amount of money from the amount gamblers I dispute what you say.
When gamblers bet in the casino on just one type of bet, only 10% of gamblers can win from the total who participate in that one type of bet, whereas in casinos there are many types of bets.
When we study that in every casino game, not many gamblers win and almost all gamblers experience defeat more often, and it is clear that the gambler's losing money is an advantage for the casino.
So are you sure that the casino's advantage is so small that it really can't afford to give big bonuses to players?