with gambling you will have many losing days, even if you manage to turn the house edge in your favor by some miracle. You would need a good amount of money to avoid going to bankruptcy if you get few bad days, that is, you would need to risk some good money one way or another
Over time gambling is a certain loss. There is no online or offline casino's that don't have a edge for the house.
Also with bitcoin gambling there is not really a regulatory body that keeps casino's honest. On half of them how do you know there is not a guy at other end picking if you win or lose? It requires more trust then I'm willing to give.