There are no more demand for this kind of PVP Gameplay, You need re-invent your project and follow the current standards set by the different casino platform today.
The 5% Fees is high considering you are not risking anything on both sides of the bet, 0.20% to 0.50% is pretty much the current standard.
Agree, primedice used to offer a flip feature that had zero fees if i remember but they got rid of it. Do a zero fee flip site and use ads/donations for profit IMO.