Earth population: 6.5 billion.
Chance of 4 billion people having a credit card = close to 0.
So taking all the sponosors combined, they wouldn't make this many sales in a few years ;)
Actually it's kinda interesting.. if you assume that online porn industry is 5 billion a year (i dunno the exact numbers), and each signup is at $30, counting recurring as multiple signups, all sponsors in total push about 170 million signups a year ... kinda cool
