MORE: Warren Buffett is still a pretty good investor Billionaires are flying private more often. Buffett's private jet company, NetJets, grew very little because fewer new customers bought planes. Still, only a small segment of wealthy individuals can afford their own planes, and Buffett was encouraged by the fact that current owners appear to be using their jets more often, something that declined during the recession: "The flights have picked up — the owners are using the planes more in the last six months to a year," Buffett said. Self-driving cars threaten Berkshire Hathaway. There are few things that pose a competitive threat to Berkshire Hathaway, and Buffett and Munger are loath to admit those threats. Still, there's one development that could put pressure on Berkshire, according to Buffett: self-driving cars. Buffett is a huge fan of longtime holding GEICO, the auto-insurer. But the question of auto insurance for self-driving cars that don't crash has not yet been answered.