Myth, pure and simple. The slots are limited in numbers. Actually the casino is going to be relatively small, with only 1,960 slots. Most Vegas megaresorts have closer to 3,000 slots and more tables than Wynn will.
Steve is working hard to make sure people realize this isn't just about gambling, its about experience. With rooms likely going for over $300/night, 18 restaurants he owns (not leasing out like others), and a bevy of high-end shops, he will get plenty of money out of guests. The high rollers he all still knows and attracts so he won't have any problems making good coin from the casino anyways.