There must be a reason why Elon Musk made this statement because this coin, ETH is not a scam coin and the coin is just going through some though times from which it will soon recover.
I do not know what he was guided by, stating that ethereum is a fraud, however it seems that he does not understand cryptocurrency. I had a better opinion of him before that. Yes, a person can not be an expert in all areas, too much specific knowledge has accumulated humanity.