There is a type of fraud which lures investors to pay and earlier investors get that money. What are these schemes known as?

Financial exploitation is when your money is taken by deception or other means rather than by outright theft. Though deception is the most common form of financial exploitation, threats of violence are also used.  Financial exploitation is all around us: online, on your phone, at your doorstep or just about anywhere else. You must always be on your guard against it.