I don't think we can totally change the misconception many people have about Bitcoin that it is a Ponzi scheme especially people that lost their money to Ponzi scheme investments that used Bitcoin as a means of payment. The person who introduced to Bitcoin was a victim of failed Ponzi scheme investment of which Bitcoin was used as the payment method and because the majority of the people who lost money to that Ponzi that time didn't have the courage to study more about Bitcoin, they all believe today that Bitcoin is a Ponzi scheme but put of curiosity of understanding the whole procedure at which they were scammed, he learnt about Bitcoin and understood that Bitcoin isn't a Ponzi scheme rather a scammer used it as a means of receiving payment of his Ponzi scheme.

When you can't convince these set of people, it's better you allow them to continue believing what they think is right about Bitcoin than to have long arguments with them. The truth is that most people who are currently against Bitcoin today and have refused to learn about it will one day pay to learn about it.