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% so the bonus allows you to play with a 3% house edge instead of 5%.
If we look at it the way you describe it, I think it's better not to have the intention to claim this kind of bonus. Although I always dislike depositing into a casino based solely on the bonus.
Because I haven't been able to claim the bonus to date, and most of the time, if I deposit on the bonus, I've faced losses, especially when trying to fulfill their wagering requirements. That's why I mostly stay away from betting on normal deposits and also try to join free events at good casinos if they have them. Moreover, if the wagering requirement is the same amount of deposit, then I think the bonuses are actually authentic, so I also think it is not a pure bonus.
