People usually know what Ponzi is about so comparing unrelated things to it is going to be obviously wrong. But most people have very murky idea beyond "something in capitalism went bad" when talking about the subprime crisis, so any time anybody wants to criticize anything going bad in capitalism, they are free to grab this example with low(er) risk of being called out.
I was thinking of a Godwin equivalent for finance, which is narrower than capitalism as a whole.
What I had in mind is that once you take several rounds of investments (especially from private individuals) and are not profitable, bad faith critics may try to picture you as some kind of Ponzi scheme (trying to repay early investors with late ones, etc.)
Well, the trick of Ponzi scheme is that it looks externally exactly like legit financial company - you get investments, you pay dividends, you attract more investments to finance growth - this is how many legit companies work. Without looking inside - whether or not the company has legit activity going on on the inside, whether currently profitable or not - it's impossible to know, externally it looks the same.
