That's a simple site but it works fine. Is cool to know how we can get 0.00166 daily if you invest 1 BTC, it means the investor can get more than 0.5btc/year with 1 BTC, and that sounds too good to be real :p
Since we are talking about gambling some months the casino can end with loses, and that happens when some whales win big. But most of the months the house ends with profits.
By the way, it would be nice if you add a tab with info about the project, it would be nice to know the equation you use to do the math.
I believe it would be reasonable for us to assume that Bustabit and other casinos which offer the options for gamblers to take a slice of their profit by providing liquidity, have some part in their Term of Service which states that the Percentage of return could get adjusted without previous warning by the casino operators, it is similar to what happens in cryptocurrency exchanges which offer interest for deposits in stablecoins and Bitcoin.
So even though these numbers sounds pretty impressive a first glance, that percentage could get adjusted for the sake of the long term sustainabilty of the casino and investors.