Not true.
If 10 people invest $1000 each and the promoter runs off with the money, everyone loses their money.
And even if the promoter pays out interest, they will have to make 10 payments before the investor breaks even.
If people want to invest, it's their money they can do what they want with it, but there is no such thing as a honest Ponzi; they are all scams.
There are honest ponzi games. If the operator declares that his/her game is a ponzi and the last investors will lose money, then every participants will know what going to happen and then they can invest accordingly. Sites where the operator babling about external profit sources and investments are the really dangerous ponzis.