To be technical, there are multiple inaccuracies in "Get 120% back when the next person sends".
First, as per the central problem of Ponzi schemes, it is missing an "... if ever" at the end.
But further, it is oversimplified, because people can submit different amounts of bitcoins. Covering up that uncertainty -- which while apparent is not as clearly disclosed as the "Ponzi" aspect -- makes it harder for people to assess the likelihood they will get the promised return.
I think the completely honest thing to do would be to show another number (total sent * multiplier), explaining that if you send now, you will get the amount back when the total counter reaches that amount.
First, as per the central problem of Ponzi schemes, it is missing an "... if ever" at the end.
But further, it is oversimplified, because people can submit different amounts of bitcoins. Covering up that uncertainty -- which while apparent is not as clearly disclosed as the "Ponzi" aspect -- makes it harder for people to assess the likelihood they will get the promised return.