Here in cyberworld scammers and spammers are rampant which those people can think bitcoin is not exist and to think that it's just a ponzi scheme.
i just see that bitcoin is like gold but in digital form, so if you think that bitcoin is a ponzi scheme maybe gold is a ponzi scheme too, hahaha. it just my opinion i dont know people think about bitcoin and i hope your argumetation with your friend will clear soon