Well, based on past experience I've had with crypto exchange, I won't completely lay all the blame of the op, like I mentioned in my previous comment above, there is the chance that the casino would have mistakenly sent those funds to another wallet, possibly due to the staff in charge wrongfully copying and pasting another wallet in their withdrawal system..
I don't get it. You need to specify your withdrawal address when you are trying to withdraw anywhere. Why would the site automatically select an address?
Back in 2017, I was withdrawing 28 usdt from a crypto exchange, and the withdrawal went into manual mode after some time, I was wondering why would the exchange pass a 28 usdt withdrawal request into manual mode, I kept my cool and waited patiently, after about 5 hours of waiting, I got a wallet notification informing me I have received 28 Ethereum coins, I checked my wallet and could not believe my eyes, long story short, I later had to return 25 of those coins to the exchange, they asked me to keep 3 as a reward for deciding to return it, and they still sent me my 28 usdt withdrawal..
This is a crazy story. Mad respect to you for returning so much money since most people wouldn't have done that frankly speaking. You deserved a bigger reward(Example: 10 ETH).