A large pool of people paying premiums allows insurance companies to have a larger social media following

If a large pool of people pay premiums, insurance company employees will get more bonuses included in their next paycheck

The premium payments of all the insured clients will cover the costs for the emergencies of the few who need it

The more people that pay premiums, the more careful each insured client becomes with their lifestyle choices

Insurance companies use calculus to find out how likely a client will need to use the insurance so they can set premiums in order to have the highest chance of making a profit

Insurance companies use algebra and geometry to calculate the distance from clients' major emergencies to the nearest hospitals

Insurance companies use statistics to find how likely a client will need to use the insurance so they can set premiums in order to have the highest chance of making a profit

Insurance companies use statistics to hypothesize how likely clients are to switch over to competitive companies

Risk pooling

Risk management

Premium collection

Comprehensive coverage

State governments

Local governments

The federal government

No one -- they exist only in the market economy with no regulation