The primary issue is to run the portal without upfront money.
This is what majority's concern right now, everyone is looking for platforms that has a secured fund to run the company, be it an exchange or a casino. Many are asking for proof of funds and if this is your primary concern to run the casino without having money to prove that you can pay winners, I doubt it that there will be those folks that are willing to risk their money and deposit it to your casino.
If someone wins a game, the admin must pay the amount to build the reputation.
Of course, you have to since you're the house and that's the usual transaction that happens from a casino when someone has won.