1. Yamaguchi Gumi—Revenue: $80 billion
The largest known gang in the world is called the Yamaguchi Gumi, one of several groups collectively referred to in Japan as “Yakuza,” a term that is roughly equivalent to the American use of “mafia.” The Yamaguchi Gumi make more money from drug trafficking than any other source, according to Hiromitsu Suganuma, Japan’s former national police chief. The next two leading sources of revenue are gambling and extortion, followed closely by “dispute resolution.”
http://fortune.com/2014/09/14/biggest-o ... the-world/
its not so convincing though....