As some others have pointed out, a "Ponzi scheme", by definition, requires initial monetary investment, which is then used to pay the first investors, so those entering last are burned. No initial investment, other than a little typing was required. If you're going to call DO a scam, at least be more accurate.
This is not true. You need to own coins to get anything from "a little typing". So it's a ponzi with extra work involved for those who are being ripped off.