Bitcoin is a fraud or a ponzi scheme has been out there for a while now but to be honest fewer and fewer people are thinking that way. I think the only way we can beat this thinking is by properly educating people on how the block chain technology works and what Bitcoin is, what is the purpose of Bitcoin and what are the benefits of getting into crypto currency. Now if the people you are trying to teach does not change their mind then let them be. Sooner or later they will realize that they are wrong about crypto currency.