Thanks for calling me a complete moron.
Now to why Disney can hold more than Huston.
Lets look at the two major factors that everyone can agree on:
Transportation
Lodgeing
Transportation
The capactiy for approx. each Disney bus is around 35 people. Each bus runs at intervals of 5 mins on most days durring closing and such. 60 mins/ 5 min intervals= 16 buses and hour. Times 35 and 16 you get 560 people per hour on buses to each hotel. FIRST had around 5 hotels they used. 5 X 560= 2800 people per hour out of the FIRST stadium. Around 20,000 people were there last year, leaving at varaying hours. Each hotel was less than 20 miles from Epcot. This allows for people to easily get to and get out of FNC (FIRST Nationals Center, my little name for the competition location) and get to their hotels FAST.
Lodgeing
There were around 5 on and off site hotels that held FIRST kids. I don't want to look up nor find the occupancy of each room and how many rooms were reserved by FIRST teams. But with two cheep places to stay (All Stars and the new Pop Century), many teams won't spend more than $60 per nite in a good room.
Lets not get into entertainment. Each park can hold anywhere from 50,000-90,000 each.