> But even if some hacker gets to the accounts... the stolen funds will be immediately returned by the receiving bank, with apologies.
Probably in digital form with no collateral to back it but If Soros were to pull it out I bet it would create one hell of a deficiency.
Not really. Sure, a hacker can steal $1000 from someone, transfer to his bank in Nigeria and withdraw it as cash without much effort. But what will he do if he stole 1 million dollars? (That's the smallest coin in Soros' purse.) He, perhaps, can transfer this money into Nigeria... with all red lights and sirens blaring, because his account is not a commercial one. But let's imagine he has registered a company, and he transferred just one million USD into it. What's next? How much money can he physically spend if all he has is paper? Does he have a gold mine already selected that is for sale? Or a bunch of custom made Ferraris? One simply cannot spend that money fast enough; and chances are very high that he will be invited to his bank and his income discussed, with police from the division of financial crimes present.
In other words, the hacker's time window is too small to do anything useful with the money. He will most likely never see it. Hackers survive only because they do small stuff that flies under the radar. Do something big, and it crashes down.
So the stolen money (the numbers in computers) will be perfectly safe for an eternity in terms of banking - for days, if not for weeks. Once the theft is discovered, the receiving bank will simply reverse the transaction because it has the money. I cannot imagine that the bank would be stupid enough to receive a huge sum of money and, before its fate is clear, lend it all out.