Only 20% of the funds went into mixers. If I had to guess, the attack was done by a group of people and they split the funds up. Some of them were smarter than

Only 20% of the funds went into mixers. If I had to guess, the attack was done by a group of people and they split the funds up. Some of them were smarter than others. It's also possible that the people who have been arrested are simply people who have received stolen goods (knowingly or unknownly). Perhaps they traded something else of value for the Bitcoin and didn't know how dirty it was.