Modern hedging techniques are widely available; I believe these guys belong to trade associations that explain how to use them and/or they talk to dealer friends they know and trust.
That article didn't say anything but others did: they used leverage and promised low-teaser prices to attract buyers. So phoney pricing plus leverage.....what could go wrong ? You need slowly rising (or falling) prices in that situation. You can't "promise" people gold profits because you never really invested their $$$ in the product.