If you go to an IRL casino with a Poker room/table, the casino will take some amount per hand, even though the players are all playing against each other, and the casino is not risking their own money.

I applaud the PvP model, and think this kind of betting is more fun than playing vs the house.

I do believe it is appropriate to charge users some fee for using your casino, but this may be much less than what "traditions" bitcoin casinos charge. If you have enough volume, a .1% of 0.01% "edge" might result in you turning a profit.

There is a reason many in this thread have pointed out that relying on donations to fund your business is not realistic. Because this is not a viable business model. The "zero edge" will also make players suspicious.

Good Luck!