The paintings by Picasso, Matisse, Braque, Modigliano and Leger stolen last Thursday night from the Musée d’Art Moderne de la Ville de Paris, opposite the Eiffel Tower, are immediately recognizable and, therefore, difficult to dispose of. The public assumes that the purpose of the heist was to blackmail the museum or insurance companies to pay the heisters whatever they demand, as soon as possible.
The public does not know what this blog knows. In the world of organized crime stolen works of art enter a shadow economy and are used as collateral or as a form of payment for purchases of guns and weapons. It may be years before they will see the light of day and become the objects of ordinary, common-garden blackmail.
Eric Koch’s book, The Weimar Triangle, is available at Indigo-Chapters and in your local bookstore. 
In the past it has happened that some pseudo-collectors would keep stolen works of art in their basement and then spend hours looking at them. It takes a weird person to do that sort of thing.