Warren Buffett and Bill Gates at a Berkshire Hathaway annual shareholders meeting. Rick Wilking/ReutersBill Gates and Warren Buffett have been friends for over 30 years.After hitting it off in their first meeting, they worked together on philanthropy for decades.But their relationship appears to have cooled in recent years.Warren Buffett and Bill Gates, who both rank high among the richest men in the world, have been friends for decades.