there might be some scope of expanding the payment domain a little beyond BTC? I'm just thinking of fees, here, it may be worth considering other blockchains also

We might give an option to withdraw in other cryptocurrencies but the main option is Bitcoin.
We might offer withdraws with other cryptos like LTC but with a % as fee
i like how you prioritize bitcoin more than anything else and maybe this is the reason why you are charging extra fee if users prefer alts instead of btc , this idea can force players to gamble with btc only if they really find the site entertaining .