I think one very important thing Warren Buffett found, is not the use of float in the insurance business, because people have been operating insurance business for many many years, it is crazy that they don't understand the power of float. It's just that they are limited by ways of deploying the capital, to certain safe and liquid products, e.g. fixed incomes. But it is not a problem for BH. Why? Because Warren is actually leveraging 1)operating business that is cheap, safe and with ok ROEs, that sits with a lot of cash and cash generating capability 2) non-matching assets and liabilities, and a portfolio liabilities with different fulfilling duration/risk/probability. This is really the secrecy and difficult part - to construct a portfolio that essentially is highly leveraged, but in a consolidated fashion and hedged/risk-allocated "beautifully" with enough cushion. That is also why super-cat, general re and the likes are very important to BH. On the liability side, it must have been really a masterpiece in the history of finance, but almost never get enough exposure, not to mention credit.