In your case it doesn't affect you. But it affects the player. If someone deposits 5 bitcoins, wins a couple of games and withdraws 2btc it equals a loss for that player. It won't be fair towards the player.
How though? 5 bitcoins = 115x5+15% bonus. Thats $575+86=$661.
He has 661 in his account to bet with. How does this affect the player? Again, I am not being critical, I am just trying to understand how its wrong.
If he wins 339 he has 1000USD which I convert to BTC. which would be 8.69BTC
If he loses 361 and had 300 left and wants BTC, I convert the USD to the appropriate BTC which would be 2.60 . How does this affect the player?