I can't put a number on it, but I don't think it's hyperbole to describe the LIBOR manipulation as theft at an almost unimaginable scale. One issue with too big banks, a too big banking system, and generally asleep regulators, is that the amount of money to be made by shifting any key rates by even a tiny unnoticeable amount is huge. A teensy percentage of a trillion dollars is still big money.
Free money for the Great Casino, government backstopping of losses, and legal means to take a chunk of every transaction aren't enough for them. They want to steal some more.
But they're extraordinary people, so what's to be done?