He didn't say that. That's what the author of the article said. Of course Warren buffett doesn't like it. He has made his name on being able to tell if a stock's price is above or below it's fundamentals. Bitcoin doesn't have fundamentals and it doesn't pay dividends.
`Metcalfe's law states that the value of a telecommunications network is proportional to the square of the number of connected users of the system (n2)` https://en.wikipedia.org/wiki/Metcalfe%27s_law