It's his job to be strategic about buying and selling, but Buffett also said he can understand an investor who will make a few good investments and hold on to them forever. That could be the right decision for many investors who don't have Buffett's day job.

Warren Buffett donated on Friday another $6 billion of Berkshire Hathaway stock to the Gates Foundation and four family charities, his biggest annual donation since he began giving away his fortune nearly two decades ago.

The soon-to-be-former CEO of Berkshire Hathaway has donated 12.36 million Berkshire Class B shares, worth $6 billion, to the Gates Foundation and four family charities. The Gates Foundation received the majority of the shares, with a gift of 9.43 million.