I can spin it every 12 hours and usually I get 1 BFG, occasionally 3 BFG, and I got 10 BFG just a few times.
It looks like the biggest win that users have managed to get from this wheel is only $24 in BFG tokens. Apparently, the chance of such big prizes as 1 ETH and even more so 1 BTC is too small, and hardly anyone will be lucky enough to win them. I guess the chance of winning such prizes is 1 to 1 billion or something like that.