The shell game, or cups and ball game, is largely considered to be a scam. A practice only the shadiest of street gamblers produce under the guise of an actual, winnable game. But it's not.
Not even this wooden robot will give you a fair shot. It's probably got some sort of mechanized magnet, triggering randomly to drop the ball in a different cup on each release. Or maybe it's magic. Whatever it is, it certainly looks nifty.