Technically depositing money at an online casino is not an illegal thing.
Why do I say so? Simple, coz technically you didn't gamble online. You just put money in there. Now, I don't really remember the law correctly but if I'm not mistaken they say it's Illegal To Gamble Online which you did not do. You merely parked your money there.
So, technically you have not committed a crime yet. It's like you wanting to steal something from a store. Even if I put the thing in my pocket and etc, as long as I didn't walk out of the store and I'm within the grounds of the store, I'm still not a criminal. Unless of coz I step even a foot out of the store, then I can be considered a criminal.
In truth, if you call up your bank to ask for the charge to put through they can only tell you that they could not allow the charge to go through because of this and that. That's all they could do to you. Even if they report this to the DoJ or Feds or etc, they could not convict you of anything because the bank has already denied your request and thus you did not gamble online.
In the same view if your bank did allow the charge to go through, they will be in trouble more than you if/when the DoJ or Feds are involved. They know that allowing online gaming transactions is a grey area (or might even be illegal) and they allowed it to go through. So if they actually allowed it to go through and they call the Feds/DoJ on you, they will be roasting themselves instead of just getting you in trouble.
Ps. winbig, I would like to take you up on your odds of 2000:1 with $10. I doubt anyone will even get in trouble for doing this.