I thought Dropbox's revenue mainly comes from it's business clients - B2B is more $ compared to B2C although B2C might be more profitable as customers might pay the $10/1TB and not really use that much anyways)
Their paying users have increased, but the revenue per user has decreased (based on the S1...which I assume is because of enterprise deals).
Their paying users have increased, but the revenue per user has decreased (based on the S1...which I assume is because of enterprise deals).