Definition of 'Pyramid Scheme'
An illegal investment scam based on a hierarchical setup. New recruits make up the base of the pyramid and provide the funding, or so-called returns, given to the earlier investors/recruits above them.
Investopedia explains 'Pyramid Scheme'
A pyramid scheme is initiated by an individual or a company that starts recruiting investors with an offer of guaranteed high returns. As the scheme begins, the earliest investors do receive a high rate of return, but these gains are paid for by new recruits and are not a return on any real investment.
From the day the scam is initiated, a pyramid scheme's liabilities exceed its assets. The only way it can generate wealth is by promising extraordinary returns to new recruits; the only way these returns can be paid is by getting additional investors. Invariably these schemes lose steam and the pyramid collapses.