One critical point:
Insurance is a product that certain businesses produce for trade and profit. Insurance companies price their product by assessing risks and accounting for many variables involving the market and their customers. Insurance companies and their customers (properly) deal with each other voluntarily, by mutual consent to mutual advantage. Insurance, properly speaking, is a kind of voluntary contract.
The coverage for “pre-existing conditions” that insurers are forced to provide is, strictly speaking, not insurance at all.(For more, read the full text of "The Solution to 'Adverse-Selection' in Health Insurance is Selfish-Selection".)