By their name, pyramid, the person at the very top may make some money, but as more people join, and the pyramid gets wider, you need thousands of people to join to get any money back.
You reach the stage where you would need half the population of the UK to join up to make any money.
This is what happened on the Isle of Wight a few years ago, they ran out of people and it collapsed.
http://news.bbc.co.uk/1/hi/business/1298197.st m
Most people finish up poor gullible suckers at the bottom of the pyramid who just lose their money.