Most scams might have a terrible success rate, but the scammers still make a lot of money. Over $80mil in scam losses were reported to the Australian Government last year, s surprising amount were from Nigerian style scams and the like that you'd think nobody would fall for. For every person that is willing to send money via western union to some guy in Nigeria, there would be thousands who would click through these links.
I have seen probably 5 or 6 Facebook friends fall for this one. The typical profile is of a mother who isn't very tech savvy but likes the idea of free stuff.
2011 Scam report by Australian Government is here: http://www.accc.gov.au/content/index.phtml/itemId/1039349 I've passed your research onto the authors of this report, thanks for sharing it.