Are you sure that you were in a D&B vs. CEC? D&B doesn't use coins/tokens! They use a card swipe system, no quarters. Many of the machines cost several dollars per play.
They make money based on all aspects of the business, the arcade/redemption games are just a portion.
I eat a steak with my wife while the kids hit the arcade! It costs about the same as a babysitter these days!