Brilliant! That's what I'm trying to understand.

If you say that the value of the system, and the perception of its value doesn't affect the fact that it is a Ponzi scheme, then you'll have to bite the bullet and say that Bitcoin is also a Ponzi scheme.
Anything can be a Ponzi scheme. A trading platform/exchange can be a Ponzi scheme, as we saw with Mt.Gox. That doesn't mean that all exchanges are Ponzi schemes.

In my thinking I came to the same conclusions. Thank you. I will read your other posts.