There's nothing bad in the casino providing the crypto balance in fiat cause it will even help the gambler to manage his budget very well rather than gambling more than she can afford to loose.
It is true that gamblers will be able to manage easier when he/she knows the value of his/her crypto in fiat rather than the crypto itself. Well, it's up to gambler's choice whether he/she likes it or not but if the gambling platform prefers to show the value of crypto used in fiat then the gamblers will have to use it.
When the BTC convert to fiat you gamble against the crypto value.
I will wait to official replay from them. Maybe they do have option to bet in BTC
There's nothing bad if there's no option to bet in cryptocurrency since the fund value will always increase in price footing Bitcoin value in the market through this can also have disadvantages but something most new gambling does in the crypto investment.
In the meantime, I will advise you not to use the site until the OP provided an answer to my question.
I remember the same with betnomi, one of the casinos here. Your balance is shown in USD. But you can deposit/withdraw with your chosen cryptocurrency available in their platform. So it is up to you how you can manage your bets but at least you already know how much USD you are spending for every game. As BK8 is already an established casino, most of their existing players already adopt this system.