Get-rich-quick scheme

A get-rich-quick scheme is an offer, plan, or purported business opportunity that promises unusually large profits or rapid wealth for little investment, effort, skill, or risk. The term is commonly used as a broad label for deceptive or fraudulent investment, work-at-home, and other money-making offers.

The phrase get rich quick was used in connection with dubious investments by at least the early 20th century.