Royse is right here, they ^{Blackjack.fun} have been around for a long time and there have been no serious complaints about them, at least not on the forum. This gives a certain amount of trust.
What is debatable is what this staking is for, because the investors' funds do not participate in the casino bankroll, the profit does not depend on the winnings, and there is also no risk in the case of large winnings of the user.

Royse777, keep in mind that their withdrawal fee is quite high, for example, currently, it is 0.00288081 BTC. Although the staking funds are not locked, it is certainly not an option where you can withdraw funds whenever you want.