A lot of people I know also think bitcoin and cryptocurrency are scam and ponzi but I just let them. I don't really care, I don't let them even know I'm into it. Just keeping myself, I'm earning good money and I can see how cryptocurrency changing the first world and I want to be part of this development and progress
Just as you can not wake up a sleeping person, there is no way you can change some misunderstandings about bitcoin. Since they think bitcoin is a Ponzi scheme, you do not have to be bothered either, as you naturally believe when you have accumulated some assets through bitcoin.