Duelbits is a very good gambling site, but there are also other good gambling sites on this forum like Trustdice, Livecasino, Rollbit, Roobet and some other ones too.
Unfortunately Duelbits, Rollbit and Roobet are not the casinos that fit to what is wanted by OP. As far as I remember these 3 casinos convert user's deposit into usd although players are still able to withdraw as the currency they use to deposit. I'm not sure about Trustdice and Livecasino as I have not tried them yet, but it they have the system like the other 3 casinos, means that OP will not be willing to use them too because he want to keep his balance as the crypto he deposit.
Casinos like sportsbet have the option of gambling with crypto directly without converting them to USD balance in your account so he can have a look at it and it's one of the most famous crypto casino with sportsbook option as well.There might be others but what OP is looking for sportsbet.io is good option for him.