I agree with you, and I think most other players also don't use ETH and erc-20 tokens for gambling. The problem is that the fee in the ETH network is too unpredictable, given that it might be either 5 gwei or 1000+ gwei throughout the day. By the way, I just now noticed that Betfury sets 0.005 ETH(~$9) as the ETH withdrawal fee, while the withdrawal fee for erc-20 tokens is $3.2. As for me, this is a strange decision by the Betfury team as the withdrawal fee for ETH is clearly overstated, while the withdrawal fee for erc-20 tokens is understated.