As Nassim Taleb observed, the problem here is no skin in the game. Bankers keep the upside, but shareholders have to carry the can. It's an agency problem. The fix to all this is dispensing some good solid jail time.
Graeber has an observation on a different part of this: the penalties are never greater than the profit that triggered the penalties. We're basically telling the bankers that "it's okay as long as the government gets a cut of the loot".
Are you sure? In the most recent case they had to return all $2B taken from customers and pay a $1.7B fine.
I'd be willing to look at evidence to the contrary. (Cynicism is not evidence)