You can either make a bitcoin casino or a crypto casino which has most of the established coins.
But there's no point in making an ethereum casino at all. ETH fees are huge when the network is congested.
People would rather stop gambling on your casino at times like these which would directly result in a loss of revenue for you.
So the best thing to do would be to create a crypto casino but even then there are so many casinos already.
So the competition is really tough. Might as well think of something unique but a n ethereum casino is a bad choice.