Between that small fish, there will be the whales but the casino owner will not know who is the whales on his casino. When the casino owner can have thousands of members, that doesn't mean all members will be small fish. The percentage of the whales on that casino will not be too many but that is worth it if they still give them comfortable playing many games and give the best services to them.
The casino owner will likely have more members, no matter if they are small fish or whales because if the casino owner can give the best services, sooner or later, the whales will show up to them and play using the big money that was already before.
But what the casino wants is addicted people to gambling who will gamble on their site day by day and of course, they will use so much money to gamble. These members will enjoy on that site and playing many games and if there are new games, they will play longer than the other, especially if they like the games.
The reason gambling sites do promotions as attractive as possible and provide the best service, this is done to attract the attention of many people.
So that many people come to play, gambling site owners sometimes spend quite a lot of money on promotion costs. It was done to attract
whales, because as you said from many people who join gambling sites, there must be some whales that will join in as well. The problem is
that it is not easy to detect the presence of whales, unless the whales are comfortable playing on the gambling site and finally make a very large
deposit. It would be even better if eventually there were whales who were addicted and spent a lot of money on the gambling site.
This is why many gambling site owners do various ways to make their platforms popular, and provide the best service to its users. That is to
make gamblers comfortable and not think about moving to other gambling sites, especially if the gambling site manages to get whales on their
platform, it is a jackpot for gambling site owners.