All transfers have tracking information and source/destination information. Not only would your withdraw request be denied (insufficient funds), but also they would identify that it wasn't an internal transfer.
2) Withdraw $888,888.88
3) Armed with a bank statement showing this transaction, and everything that's online about this magic number, threaten to go to the media with your story unless the bank "refunds" your missing money. The bank doesn't want to lose all its customers so it gives in, even though it knows you're ripping it off. Kevin Spacey plays the bad guy.
Good enough (maybe, just) for a movie script at least. In reality I'm sure step 4 is "Go to prison".
What if that amount was fraudulently taken from a large balance account, would the bank notice or assume its part of a fraud investigation?