We have been self-insuring for the last 6 years, 10+ properties. We take the balance that would have been paid to the insurance company minus the taxes we now have to pay and keep that in a separate account gaining interest.
We save app. $15,000 a year by not paying the insurance companies, so we have banked app. $90,000 that would otherwise have gone out.
The policies we had all had large deductibles, which we almost never met, and when we did have a water damage claim, the company, AllState, took the deductible out, paid us a few bucks, and promptly cancelled our policy.
We got fed up and changed our way of doing business. We have saved more then enough to rebuild a house completely destroyed by fire, which statistically almost never happens.
In addtion, we moved all the properties under a corporate umbrella and bought a liability only policy which covers all the properties for up to 3 million. The cost for this policy is under 2000.
Insurance companies make money by fueling your fear, you must have it, and protecting their profits, refusing to pay claims or not meeting deductibles, it is a complete ripoff and as a business you should look at the cost/benefits of dealing with them or not.
For smaller holdings, and of course mortgaged properties, you may not be able to completely self-insure, but it is worth looking into.
Buffet didn't get rich by paying claims.