Thank you every one for your comments...if someone want make an offer please reach in private, it will be listed maybe in a second time.
For what I can understand, Of course this is not a "pure bonus" but there are no limit for cashout this amount (it's still a big bonus... It can be cashed out also in small chunks)
Well, in any case the player could play also 1.01 odd ... its not a 0 win since he has the chance to opt in for a very low odd.
Even with 1.01 odds you are very likely to lose the balance withheld along with the bonus. The house edge is 5%, meaning you are losing 5% of the amount you wager on average. Here you don't need to wager it one time or even 10 times but 50 times, that is to say 25 times your bonus added to your balance withheld. Meaning you need to wager 0.050BTC for a 0.001BTC bonus while with the 5% edge you are going to lose 0.050 x 5% = 0.0025BTC on average. I'm not saying you've absolutely no chance to save something but it's very hard. If you like playing multiply BTC game it's better than nothing though, because instead of losing 0.0025BTC for each 0.05BTC wagered, you lose 0.0025-0.001=0.0015BTC only thanks to the bonus. 0.0015 / 0.05 = 3% the bonus allows you to play with a 3% house edge instead of 5% actually.
Thank you Saint-Loup for these details.
I have not much experience on that site, but are you counting also reaward point (1 or 2 each 1000 satoshi wagered?)
Since there is no a minimum odd to be used I don't think this is really too hard to achieve ( so I don't think people could loss both bonus and amount that they need for activate this bonus). It would be funny see some calculations on this made with a Monte-Carlo simulation or similar methods.