I'll ignore them, they aren' worthy of your time and effort because these type of people are close minded and no matter how good you educate them, they won't accept it, it's not my lost anyway its there's. For me, what matters most is that I know bitcoin isn't a scam and if people will insist it's a scam then let them be, i'll do my thing and I know they will only swallow there words and realize that bitcoin is 100% legit and very far from scam.
Basically we cannot blame these people that are having a difficulty in trusting cryptocurrency. As it is their main coping mechanism to avoid putting themselves to risk. In my opinion, we should think of the way where these people should be the one to approach us and ask what cryptocurrency and bitcoin is. Instead of talking to them about it like we really want their participation as it induces a feeling uncertainty to them.