A Ponzi scheme is a type of investment fraud. It works by paying returns to earlier investors using capital from newer investors. The organizers aren't running a legitimate business that earns profits. Instead, they just shuffle money around to create the illusion of a successful investment.

From the outside, everything looks great. Early investors receive impressive returns, which makes them happy. They tell their friends and family, who then want to invest too. This brings in fresh cash, which is used to pay the next round of returns. The whole operation relies on a constant stream of new money to keep going.

This type of fraud is named after Charles Ponzi, an Italian immigrant who ran a massive scheme in Boston in 1920. While he didn't invent the scam, his was so audacious that his name became forever linked to it.

Ponzi's plan involved postal reply coupons, which could be bought in one country and exchanged for postage stamps in another. He noticed that, due to currency fluctuations after World War I, he could buy coupons cheaply in other countries and redeem them for a much higher value in U.S. stamps. He promised investors an incredible 50% return in just 45 days. Word spread, and money poured in. But instead of actually trading coupons, he simply used new investors' money to pay off the old ones.

All Ponzi schemes share a similar structure, regardless of the story they tell investors. The core mechanism is always the same: paying Peter with Paul's money. This creates a simple but fragile financial flow.

The scheme needs an ever-increasing base of new investors to survive. If recruitment slows down, or if too many existing investors try to cash out at once, the whole structure collapses. There's no real profit to fall back on, so when the flow of new money stops, the payments stop too. At that point, the fraud is exposed, and most investors, especially the later ones, lose everything.