The 2008 financial crisis led to the Great Recession and millions of jobs lost. It took years for America to recover and many citizens still feel the ripple effects. According to Microsoft co-founder Bill Gates, though, we should be braced for another one.

During a Reddit "Ask Me Anything" last week, when Gates was asked if, in the near future, the U.S. will have another crisis similar to the one in 2008, he offered a blunt response: "Yes. It is hard to say when but this is a certainty."

He added, "Fortunately, we got through that one reasonably well. Warren has talked about this and he understands this area far better than I do."

Despite the warning, both Gates and his longtime friend Warren Buffett are generally optimistic about the U.S. economy. In an essay for Time magazine, Buffett stated that years of growth "certainly lie ahead," and "most American children are going to live far better than their parents did."