Good advice that I expect will be widely ignored: only invest in what you know.
So-called high yield investments are (almost?) always dressed-up Ponzi schemes. If you "invest" in them then please lick your wounds quietly when they implode. And if you're one of the lucky few who make money on them, don't expect me to admire your investing wisdom, any more than I'd admire the number-picking brilliance of a lottery winner.
Good to see Gaven's quote unearthed and featured:
http://www.theverge.com/2012/8/15/3243200/bitcoin-ponzi-schemes-savings-and-trustNice article!
One more thing I want to add to this issue though is that I do believe it is possible to tell the difference between a legit business and a ponzi scheme. It is not a matter of pure luck, such as a lottery.
There are clues one can use. While not 100% reliable it is the skill of a good investor that, on average, he or she can tell what is a good investment and what not.
Obviously, this is not something that everybody can do, which is why good investors are highly paid.