I believe that the American Greed connection is pretty straightforward...A sociopath/psychopath is drawn to the CON; they see trading as the guise for easy and unhindered access to client funds...In most cases (at least the ones I've seen), there is simply the pretense of trading, no real attempt to actually master the craft...Mostly, some superficial lip service given to a guaranteed return and then the ponzi begins...Fake statements, shifting clients funds around, recruiting new investors, etc, etc...IOW, all of the personality traits of the socio/psychopath put to use to get what they need with little to no regard for the victims.
According to the episodes I saw, a few sincerely tried their hands at trading. They all failed miserably. Maybe something to do with the psycho/sociopathic tendency to fail to learn from mistakes, or to accept blame for any screw ups.