I will start by saying that I am more a Benjamin Graham man than a Warren Buffet one. Every time any person asks me for which book of any kind I would recommend to read, my answer is The Intelligent Investor.
Once that is said, I didn't expect Buffet to show that he really knows a little bit about Bitcoin. But he do. Buffet loves to read financial statements. Those where there are money which goes in and money which goes out. And there is not such a thing in bitcoin. There is the blockchain itself, where the flow is shown, but fiat currency has also that -only that it is private information-.
So, if he is unable to understand why bitcoin is valued for that amount of USD, he just don't invest in it. He tries to not be investing in any kind of derivatives, neither. He loves simple things. Bitcoin is simple, but the same cannot be said about its valuation.