Listen to Nine to Noon interview with Danny de Hek
It was an email from a friend offering an investment opportunity he couldn't turn down that transformed Christchurch man Danny de Hek into a self-confessed Crypto Ponzi Scheme buster.
Since that email, de Hek has produced more than 130 videos taking apart cryptocurrency investment, which he calls a dangerous and deceptive scheme.
Recording from his Christchurch home he has caught the attention of those pushing the scheme, including death threats, and his efforts have also been profiled in the New York Times.
But because it uses the blockchain it makes it much harder to track down who is in charge, leaving those on the bottom, some of who have invested hundreds of thousands of dollars, with nothing.