It's a free world and everyone has rights to talk. Especially on something decentralized bitcoin. Because they don't have to face defamatory lawsuit due of that. So here they are talking non sense about crypto currency. But this is not the first time especially for Mr. Buffet. He has been attacking bitcoin since long time now and stopped making sense to the worldwide crypto community.

Mr. Buffet is speaking against bitcoin for the same reason Mr. Dimon did. They are from organized financial business which is being directly affected by bitcoin and other crypto currencies. But I see no sense when Mr. Gates speaks against it. Their field of business doesn't even correlate. Probably he is heavily influenced by Mr. Buffet or taken a huge short position on bitcoin's price!