If Bitcoin is a ponzi scheme, then ALL money is a ponzi scheme.

I think I actually mean currency here. A decent definition is “the most marketable thing”. Meaning, it’s the thing that most people believe to be easily redeemable for the broadest possible set of things. A currency that nobody believes in collapses. So yes, the value is increased by getting more people to believe the thing is valuable—but that’s how it works for all currencies.