I tried playing yesterday and yes I think you are right the sports betting came from 3rd party service and it requires USD to place bet that is why the token will be converted automatically but if you go the main page it will be converted to the cryptocurrency you are using. For me that is not a big deal since I wanted to place bet in USD.
Sometimes it's better to place bets and play gambling using stable coins because you know that the value of the stable coin won't change. I remember my friend, who once bet 0.1 btc on a cricket match and lost. After a few years, he regrets it because now that 0.1 btc is a big amount. He could have just held and got the benefits.
The other thing i wanna know is what is the minimum amount in USD we can play at owl?