Since taking over Berkshire Hathaway in 1965, Warren Buffett has delivered investors eye-opening returns of roughly 3,641,613% (through 2021), according to the company's annual report. That works out to a 20.1% compound annual gain over those 56 years. A crucial part of Buffett's success is his investments in insurance businesses. Buffett likes insurance companies because of the cash flows they generate, allowing Berkshire Hathaway to invest hundreds of billions of dollars of "other people's money."