Also, commercial insurance creates bad incentives leading the insured to take more risks.
And there's asymmetry of information, where the insured knows the risk is greater than the insurance company knows. That means the insurance company needs to charge more to make up for the dishonest people.
Have you checked what e.g. a long-term medical disorder will cost you year on year? For cancer, $10,000 is a drop in the bucket, and will not even cover your medical bills if you have additional money to go live in India while curing it.
Costings for cancer for the NHS in the UK are £40,000 per cancer patient per year - floating significantly up and down depending on the type of cancer, etc etc - suggesting that it's not solely down to the US's private healthcare system.
You can find similar examples of nearly unbounded. unexpected costs for nearly every type of insurance. Personally, I put a lot of stock in not dying when I don't have to, and not having to spend the rest of my life in a squat because of something I could've insured against.
Unemployment insurance generally has a limit (even if the risk you are trying to insure against is not). Is that limit within the reasonable bounds of self insurance? Probably so for many people, but maybe not for others.
Insurance is good for the really huge stuff, like giant medical bills or a house fire. For little stuff, there are so many risks that if something happens, it's probably not listed on whatever policies that you do have.
For instance, with home insurance, the potential risk would be hundreds of thousands of dollars to replace a house that was entirely destroyed. With health insurance the potential risk is millions of dollars to treat something like cancer. With car insurance, the potential risk is hundreds of thousands of dollars of liability if you injure someone. You can't exactly expect someone to keep millions of dollar lying around to cover the possibility that they get cancer or their house burns down.
- Insurance companies have a much much better handle on any given risk than you do
- Insurance companies have the scale to mean they are charging you only for the insurance you need; for insuring against costs that are variable and unpredictable, you are highly likely to over-save or under-save
- Insurance companies are prevented from price-gouging the difference (mostly, and in theory anyway) via a competitive market