Its really attractive especially to whale players that spends 1000$ per bets on the casino. They can earn huge amount from rakeback despite their game is on break even. An hour of 70% rakeback is massive which other casino doesnt offer even with their high tier VIP.
Blackjack.fun offers this deluxe benefits for everyone no string attached on the rakeback. I believe rakeback doesnt have wager requirements that makes it so good.
I would guess that this would be a short lived one here as well. They are probably doing marketing now that makes them lose money in the end, but they would gain a lot of whale people and when they drop that to a realistic level that will cause them to lose some of the whales but also retain a few of them at least and that would be great for them. I am not saying that they will change it for sure, but if they keep this up then it is going to bleed them dry and they will realize this eventually.
Gamblers may lose money but they sometimes earn money too, and paying them this much just for gambling will cause the casino lose a lot in the end.
They are not losing huge amount since they are just returning part of their profit on the house edge. They still have profit whenever players lose their bets which has a high chance of happening because they are eager to bet more to get rakeback as much as possible. This is a very smart marketing by setting a limited time on the special rakeback because gambler will focus on earning rakeback that will lead to careless bet.
Casino is already calculated this before they introduced the 70% rakeback.