In the United States, the underwriting loss of property and casualty insurance companies was $142.3 billion in the five years ending 2003. But overall profit for the same period was $68.4 billion, as the result of float. Some insurance industry insiders, most notably Hank Greenberg, do not believe that it is forever possible to sustain a profit from float without an underwriting profit as well, but this opinion is not universally held. Reliance on float for profit has led some industry experts to call insurance companies "investment companies that raise the money for their investments by selling insurance."
Formal self-insurance is the deliberate decision to pay for otherwise insurable losses out of one's own money. This can be done on a formal basis by establishing a separate fund into which funds are deposited on a periodic basis, or by simply forgoing the purchase of available insurance and paying out-of-pocket. Self-insurance is usually used to pay for high-frequency, low-severity losses. Such losses, if covered by conventional insurance, mean having to pay a premium that includes loadings for the company's general expenses, cost of putting the policy on the books, acquisition expenses, premium taxes, and contingencies. While this is true for all insurance, for small, frequent losses the transaction costs may exceed the benefit of volatility reduction that insurance otherwise affords.
The cheapest car insurance, period, will likely carry the minimum coverage required in your state. In most states, this is liability insurance only, which covers property damage and medical bills for others due to accidents you cause. Some states also require uninsured and underinsured motorist coverage, which pay for your injuries or damage if an at-fault driver doesn’t have enough insurance.