Billionaire investor Warren Buffett hasn't become any fonder of cryptocurrencies. In reply to a question at Berkshire Hathaway's annual meeting on Saturday, the chairman and chief executive reiterated past criticism of bitcoin and other cryptocurencies as nonproductive assets, with profits coming only on the hope that they can be sold on later at a higher price. The prices of such assets can "feed on themselves" but "they come to bad endings, and cryptocurrencies will come to bad endings," Buffett said. Berkshire Vice Chairman Charlie Munger was even more scathing. "It's like somebody else is trading turds and you decide I can't be left out," he said.