Makes me wonder how this site works out the calculations.
I also wonder if there was a single year where investors in a dice site had returns of 33% in BTC. Normally some data should be used to calculate returns but I don't know any website having data on dice side investments other than dicesites.com, and even for them I'm not sure if they make the whole raw data public.
Both yours and others result are insane. Really? Those figures? I think those are a lot only for a 1 BTC investment per year. I expect something lower than it. I only realized that the site was still in alpha phase, as on what is written when I visit it, so let us be patient for a while, while the OP is working on it in the background.
What you said about they use a data to calculate the returns, seems a right answer to your own question if how can they work out their calculations. You are already there in dicesites.com, but you didn't find the answer that you're looking for to your other question? But if you can't see the raw data there, then the answer would be no. They try to make it private but it's understandable since those data's can be sensitive.