> I myself don't refer to anything that isn't paying new customers with old customers money as a pyramid or Ponzi scheme

In Wikipedia's definition, that aspect doesn't seem to be strictly necessary [1]. They define it as "a business model that recruits members via a promise of payments or services for enrolling others into the scheme".

In my mind it also plays a bit of a role whether you're doing that with retail investors vs. high-net-worth or institutional players. A retail investor generally can't invest in startups, but might invest in crypto if their neighbor recently bought some and then talked them into it.

[1] https://en.wikipedia.org/wiki/Pyramid_scheme