1. Just because someone uses the word "ponzi" in a scheme, doesn't make the scheme a "ponzi" scheme. (Going to a murder mystery party does not make you a murderer.)
2. The classical Ponzi scheme involves "fraud". That means deception or an intent to trick the investors.
3. If an investment scheme calls itself a "ponzi" but is totally clear and up front about the method or possibility of payment, there is no fraud.
4. Whether a scheme requires USD or BTC or a box of bananas is not relevant in most jurisdictions. What is relevant is whether the people running the scheme sat out to commit fraud.
I like the way you have put in your logic, but most people here are not going to listen to anything and at the first encounter of the word 'Ponzi', they start screaming PONZI PONZI PONZI !!!
and in 99% cases they would be right to do so, lets face it, one doesnt just add word ponzi to ther name if theyre with legit intentions.
even if i had everyones guarantee not to be scammed, i would never join such case, and let alone invest in it, and if you would do anything but run away from it , i would consider you reckless
cheers