A gamble addict should not be in charge of such position of a teller because she will end up looking for a way in which she will feed her addiction because she lacks self control. Addiction is something very dangerous which controls the gambler mindset and thinking to use whatever money in his possession for gambling despite the consequences.
One thing that people don't know is no matter how long you have been doing something it must reveal someday. The teller thought she was playing a smart one unknown to her that it was a dumb idea because using people's money to gamble shows a sign of irresponsible gambling.
Satoshi has successfully been completely anonymous for 15 years and still counting, yet no one able to catch him.

The bank teller hasn't completely know how the banks works, that's why someone can caught him since he not able to erase all of the trace. It's why if you're not a developer and understand about cyber security, never ever do something risky.
You will get caught sooner or later.