Bitcoin and ethereum are already being used by gamblers in gambling game and the casino just provides this feature.
The digital things only use at online casinos. For the offline casinos, I think it will be difficult if you use BTC/eth at the table.IMO about offline casino's transaction, your BTC/eth must be deposited at the casino's wallet then exchange for casino's coin.
Maybe the casino's exchange rate: 1 coin = 1 sat
