Saw a documentary titled "This is a Robbery", where it descripted a robbery that took place in the early 1990's. Two robbers robbed an art museum that had a collection worth over hundreds of millions of dollars.
People suggested, how could they sell it when these are famous artworks? Typically, these are sold in black markets where the buyers are genuinely connected to Mafia or other illegal trades. They are both collectors and use the item as a sort of "Get out of Jail Free Card", where if they charged with a crime in the future, they would reveal the artworks' whereabouts in order for a reduced sentenced.
Not saying these robbers are doing the same as judging from the videos, they look incredibly thick.