Why don't I just mosey on down and rob the bank
I'm having a bit of trouble grasping the logic of his actions. From what I gather, he leisurely presented himself at the bank, presented himself without any mask of headgear, displayed his intentions and got some money. Did he have a gun ? Not specified. He then leisurely went back home while the bank, the FBI and a bunch of computers churned frantically. When finding the law at his door, he folded and waived his rights, resulting in a 4-year sentence.
Feels like he was tired of his apartment and wanted to try something else for a while. And 4 years instead of 20 - that might indicate the absence of any weapon. For sure the judge does not appear to think that he's overly dangerous.
He's a nut, for sure, but more in need of nice men in white coats than surly wardens in black gear.
Biting the hand that feeds IT
