Ponzi Scheme

What Does Ponzi Scheme Mean?
A fraudulent investing scam promising high rates of return with little risk to investors. The Ponzi scheme generates returns for older investors by acquiring new investors. This scam actually yields the promised returns to earlier investors, as long as there are more new investors. These schemes usually collapse on themselves when the new investments stop.

Investopedia explains Ponzi Scheme
The Ponzi scam is named after Charles Ponzi, a clerk in Boston who first orchestrated such a scheme in 1919. 

A Ponzi scheme is similar to a pyramid scheme in that both are based on using new investors' funds to pay the earlier backers. One difference between the two schemes is that the Ponzi mastermind gathers all relevant funds from new investors and then distributes them. Pyramid schemes, on the other hand, allow each investor to directly benefit depending on how many new investors are recruited. In this case, the person on the top of the pyramid does not at any point have access to all the money in the system. 

For both schemes, however, eventually there isn't enough money to go around and the schemes unravel.