I did an event last year where 10,000 people attended, and I sold 1500 cupcakes. The event was a cakey decoratey type fair held over 2 days. There was one other person selling cupcakes who was right next to me. Another stand was selling pies and ice cream and the fourth stand was savoury stuff. I counted on 1000 cupcakes for the whole weekend and sold them all on the Saturday. Saturday night we made another 500 and sold those by 3pm on the Sunday. The girl next to me sold 1000 cupcakes over the weekend, so a total of 2500 were sold to those 10000 people.
This year I will be making 2000, as the event will be 3 days this time. Same amount of people are expected to attend and the same food vendors will be there.
I transported them on a wheeled bakers trolley with 20 racks - each rack holds 50 of my cupcakes. I prep the BC ahead of time, transported in icing bags, and decorated at the fair. Just because it is easier to transport undecorated cupcakes in these quantities.
I have some on display under cute glass cake domes so people can choose, and pack the cupcake boxes picking the decorated cupcakes from behind me. I have since done other big events and transported the naked cupcakes in plastic boxes, getting 100 in each box in 2 layers with parchment between the layers.