Most people in Ponzi schemes are being directly mislead. They don't think it's a gamble.
Most people are being directly mislead. This is true for the vast majority of the human experience. Politics, love, advertising, the list goes on.
Why are Ponzi schemes less palatable than being fleeced by automated scripts on a sports-betting site? In both cases, people think they will make money because they are smart, when they actually will lose money because they are dumb.
I don't agree with this sentence. Ponzi scheme people probably don't feel smart, rather they've been mislead into thinking they have an opportunity to invest in something where they can't lose. And participants in DFS don't lose based on their intelligence, generally speaking.
To answer your question, though, Ponzi scheme participants are being intentionally misled by fraudsters, where DFS participants are willingly gambling of their own accord. That's the difference in palatability.