Missed this topic when it was actually posted. That's some nice calculations you made. These numbers looks nice on paper, but math doesn't always works in reality. If it would be just about maths, I had to win $200 at least 4 times - I'm rolling on Freebitco.in since 2015 and still haven't rolled main prize. Well, maybe one day. Hell, I haven't even got $20 so far, while maths says that I had to get it $20 8 times.. I also got $2 reward maybe only once or twice. Probably I'm the most unlucky Freebitco.in user, considering how many rolls I have made. While probably there is users who had to make few hundreds rolls to get $200 or $20.
We are in the same boat.
I've been a member at freebitco.in for 7 or 8 years now and my stats show that I have played more than 20,000 Free Rolls (excluding Free WoF spins).
So far, I have never won the $200 nor the $20 prize, even though I should have statistically gotten them about 5 times in total by now. If my math is correct, the probability for rolling one of the three highest numbers at least once in 20,000 attempts should be 1-(9,997,5/10,000)^20,000 = 99.33%. On the other hand, I vividly remember rolling all of the three lowest numbers at least once.
Furthermore, even my results for the $2 prize seem a bit off. I think I got it like 3, 4 or 5 times, tbh I didn't keep track, but it's definitely lower than the expected 8 times.
Maybe I am also just extremely unlucky, but the longer I keep playing, the more I am doubting the self-proclaimed fairness of the site and that all numbers have equal odds.