Pachinko isn't the huge money maker it used to be. At around the turn of the century, it was a ¥30 trillion a year business, putting it on the same revenue level as medical care, but according to the Nihon Yugi Kanren Jigyo Kyokai, the pachinko industry association, pachinko parlors now pull in about ¥10 trillion less, give or take a few trillion. Ten years ago there were about 17,000 parlors nationwide. Now there's only about 12,500.
Unlike horses and certain other racing sports, pachinko is not approved by the government for gambling purposes, but the industry has traditionally gotten around this obstacle by offering prizes to winners. These prizes can then be exchanged for cash at secretive little booths (keihin kokan-jo) located outside the premises, since having the booths inside the parlors themselves would be against the law. The businesses that run the booths sells the prizes to a wholesaler who then redistributes them back to pachinko parlors.
Organized crime elements used to be centrally involved in this buy-back cycle, but in the early '90s the police managed to lock them out of it and set up their own organizations to administer the business. It's been reported in the past that a portion of the money these schemes make go to the National Police Agency for things like pension funds. A prepaid card system for pachinko parlors was introduced in the '90s that made it easier for the police and tax authorities to monitor revenues.