Big Sporting venues WiFi question. How can a network serve such a large guest population?

We have a sporting venue with 60k seats. With back of house and office space, total clients are around 61k. During an sporting event even if only 10k people are simultaneously connected to WiFi, with 2 mbps speed, that is 20Gbps throughput. Our internet circuit is only 10 gbps. How does the network handle this load? The WAN interface, I have never seen more than 40 percent utilization. How is this even possible? Is there some kind of internal cache goin on so that end user is not getting out everytime for his content?