Bitcoin is a lot of different things to a lot of different people. The fact that it satisfies a certain set of conditions of a Ponzi scheme does not invalidate the myriad current and future applications of crypto. The social security administration could also be considered a Ponzi scheme, but it still provides tremendous value to a lot of people.
I'm sorry, what applications? Besides accelerating global warming there doesn't seem to be anything it's good at.
[0]https://www.theguardian.com/technology/2021/jul/31/out-of-co...