people have been calling bitcoin names for ages. from being dead and rat poison to things like ponzi scheme. and not "fraud". and none of it ever mattered and it will not matter when big and advanced countries like Japan has adopted bitcoin as a real currency.
in fact these people are making a public idiot out of themselves when they say things like that!

and the reason why they say these things is either because they feel threatened by bitcoin or they want to make profit from the drop. there is no other possibility.