Their analysis is based on several assumptions, however, any one of which could easily be wide of the mark. They argue that with three billion downloads on the App Store (not an assumption), 17% of those are paid apps (assumption), with a piracy rate of 75% (assumption), and the number of pirate downloads at 1.53 billion. If the average price of a paid app is $3 (assumption), then there's $4.59 billion in losses. Assuming that only about 10% of the pirates who downloaded apps would have actually bought them, that makes the total $459 million. Still with us?
According to 24/7WallSt.'s analysis, around 10% of iPhone/iPod touch users have chosen to jailbreak their devices, and it's only about 40% of these jailbroken users who are responsible for this torrent (ahem) of piracy. This means that, according to 24/7WallSt.'s numbers, out of a rough total of 75 million worldwide iPhones and iPod touches, a mere 3 million devices are responsible for the 1.53 billion apps 24/7WallSt. is claiming have been downloaded illegally.
For those of you calculating along at home, that works out to an average of 510 pirated apps per device. That snap you just heard was suspension of disbelief.