IMHO Ethereum isn't a security. you holding it doesn't give you a right to any assets of the company (in this case, the blockchain). Simply lets you make transactions on the blockchain so, the token, is a utility.

Buffet and his ilk are old school investors. they didn't invest in the tech boom of the 90's and there as sure as hell ain't going to invest in this one either.

plus i think some of the crypto projects out there are a direct assault on some of their investments' future earnings so, in my view, there's no wonder why their against cryptocurrencies.