Billionaire Warren Buffett warned people not to think investing is an easy way to make a fortune as he answered questions at Berkshire Hathaway's annual meeting Saturday.

Buffett said it can be tough to pick the long-term winners. He pointed out that in 1903 there were more than 2,000 car companies, and nearly all of them failed even though cars have transformed the country since then.

"There's a lot more to picking stocks than figuring out what will be an incredible industry in the future," Buffett said. "I just want to tell you that it's not as easy as it sounds."

Buffett has said that most people will fare better by owning an S&P 500 index fund instead of betting on individual stocks. He said many of the novice investors who jumped into the market recently and drove up the value of video game retailer GameStop are essentially gambling.

Buffett said the stock trading platforms that allow people to buy and sell stocks for free, such as Robinhood, are only encouraging that gambling.

Buffett spent several hours answering questions Saturday afternoon at an online version of Berkshire's annual meeting alongside vice chairmen Charlie Munger, Greg Abel and Ajit Jain.