Seems like there are some trading pairs which almost always favor one coin over the other. Wouldn't CFights lose money if most of the bets go to the stronger coin?
Do you have a FAQ that explains your house edge and revenue structure?
As pointed by @btcltcdigger, cfights will be charging 10% commision for all top ups and withdrawals. It's stated in their Terms & Conditions ( 3.3.8 ).
The game is a PVP as stated in the OP so cfights won't be losing money if one wins over the other player.
So in total players will lose 20% (10$ for deposit + 10% for withdrawal)? 10% on withdrawal alone is a big disadvantage for players. In addition as said by BALIK, 10% commission on deposit is an instant lose for players. Cfights needs to rework on how they should earn from site. It is better if they take a commission for every game only like most other pvp based game. Otherwise there will be no one willing to lose 10% without playing even a single game.