Two things in the Internet make more money than anything else – gambling and porn (and maybe pictures of puppies).
I didn’t have enough resources to open an on-line casino (would you like to play a game of high-roll roulette run on a server kept under my bed?). It is probably also not that legal.
Porn on the other hand… ok, I could do that. I just needed couple of volunteers, hotel room and a smartphone camera.