The only cost for maintaining a Kryptium betting house is just the blockchain network fees for publishing and updating event data on the blockchain (a few cents per transaction).
To make this project successful you should somehow make an off chain solution to public odds and events. Also should be an off chain platform to make previous agreement. And only then if both side got a consensus do the on chain contract. Because to run a sportsbook "house" you should constantly track markets and adjust lines "odds". Without that any smart player will rip off any house. If every odds adjustment will cost you on chain fees you can't effectively run the house (the biggest market and lower fees the more frequent line adjustments happen "up to 70 changes per minute at close lines"). It will just cost you a lot to run a house. It's a good idea but it need a lot of improvements to be useful.