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.

There hasn't been a mandatory upgrade of the wallet in quite a long time.  You may still compile the code from GitHub and have a working wallet.  Later, non-mandatory, upgrades to the wallet, after the introduction of DeepVault are closed to review, however if you do not wish to use that proprietary DeepVault, then, yes, the code is open source.  I think I've used DeepVault once, not a feature I really need, so, if I wanted to simply stake or hold Onion, I could use the open source, if I cared to compile it myself, from GitHub.

I dislike misinformation being spread, and I would like to know if anything I've typed is factually inaccurate.  Once I investigate your claim, I'll happily correct myself.  Now, just for arguments sake, making statements like, "I feel DO is a scam...." is not something I'd even entertain, your feelings have nothing to do with it, neither do mine.  What I want to know is, can you compile a functional wallet from open source for DeepOnion?  Yes, you can.  Therefore it is effectively open source.  Was a monetary / fiat investment required to initially join the "modified airdrop"?  No, there was not, I was here at the beginning.  A minimum is required now, with, nine, I think, rounds left to go, so, break out your Funk and Wagnall's but that fails the definition of a "Ponzi scheme".

Closed versus open source and "Ponzi scheme" seem to be the arguments thrown around the most, and they appear invalid.