Stealing $3.6bn in Bitcoin. Absolute madness, as within the group of people who have been robbed will be plenty of people willing to pay good money for these guys to be found and killed, plus any unsavory characters spotting them will know they have access to a massive amount of untraceable money. Either way these guys will need to watch their backs constantly for the rest of their lives (however long that may be). The reason heists of this scale don't happen often is because most people aren't stupid enough to put such a big target on their backs..