« Insurance companies are bond surrogates, in effect they are compounding book value at a rate that you can compare to a zero coupon bond (assuming they don't pay a dividend). Berkshire also is a bond surrogate although I've rarely heard it described that way. »
Insurance used to work that way - it was a nice little business, but things happen. Remember when the IRS refused to recognize premiums paid to captives as business expenses, that was back in the 70s, I think, and many of them expanded so they were no longer captives and drove premium prices way down? Now we have climate related events and (probably) not a real clear idea of the risks that are involved.
The flip side of risk is opportunity, you need risk for insurance to work, but I think insurance is going to be more volitile than it has been.