like his "friends" JPmorgan did some weeks ago...
It was a client buying BTC. JP Morgan themselves didn't buy BTC.
According to MarketWatch, Buffett stated that Bitcoin is not a value-producing asset and there is no telling how far its price would go. It is “a real bubble in that sort of thing”, Mr. Buffett concluded. There is a completely unjustified hype around initial coin offerings, the entrepreneur believes, and described this as a typical market sentiment when “people get excited from big price movements, and Wall Street accommodates”.
To be fair to Buffett, he may be correct that the crypto market is in a bubble, and it's not entirely unreasonable to suggest so. Buffett has always liked very simple long-term investments and prefers not to frequently buy and sell or engage in risky investments.
What he actually said about the value of crypto was:
You can’t value bitcoin because it’s not a value-producing asset.
And while we can argue about this all we like, it's not particularly subjective. There's no "correct" value of BTC, and Buffett seems to be aware of that. Perhaps he's also aware that suggesting Bitcoin is in a bubble is subjective, so when he does that maybe he's aware that he could potentially be wrong.