The Secret Power Behind Why We Pick Crowded Restaurants Over Empty Ones | Fast Company | Business Innovation

I called my cousin that evening and offered him $50 a day to come down with his mates and play with the helicopters. This was a 14-year-old kid’s dream, and he enthusiastically accepted my offer. My cousin and his mates came down every lunchtime and spent their entire weekends at the stall. I ended up selling all the helicopters by December 10. (…) I had completely sold out and had nothing to sell.

That is the power of Social Proof.