However i think that the 'high yield investments' this couple invested in are not your normal hi-yield/hi-risk investments. A Ponzi scheme-esque type of 'investment' can be termed as a high-yield investment by some (and these are either fools or swindlers), but anyone with their wits about them would not even look at it as an investment (unless, ofcourse, the person is a swindler and will use it to get money from those who would willingly part with it).
Strike the "either fools or" portion.
The only folks who tout it as a "high-yield investment" are the swindlers.