Answered the survey and recommend other coins with a minimal fee and fast confirmation, I recommend Tron Litecoin, BNB and Dogecoin, I have these coins/tokens on other gambling sites I'm playing like Stake and Betfury, but if you checked the site's stat many gamblers still prefer Bitcoin, even if the fees are high and take time to confirm.
Because some gambling sites only accepts bitcoin and people who are betting gor thousands doesn't really care about paying 2 or 3 dollar as fee, if they want to deposit other coins while they are only having Bitcoin they need to go to exchange and convert the btc into other coins which is also time consuming that is why many people don't really want to do that.
For a better option, it would be better if there are at least 5-6 cryptocurrencies that must be accepted, I guess the top 10 altcoins are considered as good.
However, mainly accepting bitcoin on a gambling website is a good step and it will contribute a lot to the market price since bitcoin is very volatile.
I did visit the site but I'm not yet fill-up the form. We know that the bitcoin fee is very high at this moment there is nothing to ask that way, different gamblers have different prefer upon using digital currency to deposit and most are don't care how much the fee of bitcoin as long as they can gamble right away. I guess, the best answer is, the more cryptocurrencies as a deposit option, the more people have an option which they prefer.