Actually, the business model is generally that they pay out roughly what they receive in premiums (usually a bit less), but because there is a time lag from receipt of premium until payout, they effectively are companies holding huge cash reserves which are invested or lent to banks etc. Hence the insurance company earns substantial sums of money from interest and investment returns on its customers' money. Imagine if you took £1billion in premiums, held onto the money for a year, then paid it all back. If you could get a 5% return, that's £50 million. A simplistic example, but one which illustrates the point.