I guess one of the easy points for them was that acquiring users wasn't that expensive (not sure how they did it, but 90% of the Internet users have one of two Uruguayan email providers, and getting the email databases wasn't that expensive last time I heard about it). They also use Facebook (By the way, I read here that Facebook ads weren't having good conversion rates, but both me and my girlfriend have made purchases based on Facebook ads. By comparison, I never bought anything off a Google ad, surprisingly).