Nope, it did happen. When they started it they had quite nice rooster of collaborating companies, and quite good conversion rates. At some point, they had 15% of the mobile ad market.

Plus, they didn't just go from 1M to $50 because nobody came to them at $1M. That was the inital price back in 2010, and just for the launch. Afterwars it was a gradual progress of opening the service and letting more advertisers in (went to $500,000, then to $100,000 etc)