And some insurance companies have a cap on insurance, so if the person exceeds the cap, they have to start paying for their treatments out of pockets. Catastrophic health insurance is a good idea.
I have seen people who have held all sorts of benefits and fundraisers for friends and family members, to help them pay for medical bills. Often, the stories are downright pitiful, when someone has worked hard their whole life, and is suddenly disabled by illness, unable to work, and out of insurance. It's heartbreaking.