Depends on your employer/occupation. You can purchase insurance directly as an individual but it's usually the most expensive way to go as you have no group bargaining power. Small businesses are also hit by this, as they're only trying to cover a small group of people.

For this reason many small businesses don't offer insurance directly, but provide a tax-free health insurance stipend to their employees who then source their own insurance, effectively subsidizing the more expensive premiums as a benefit.

Larger employers have more bargaining power due to the number of employees they bring with them and can get better rates/plans from the insurance companies, and these better rates/plans are typically passed along to employees as a benefit for working there. An employer might cheap out, but that's the same as offering a bad salary.

Very large employers (Fortune 500s and such) are often self-insured, where they contract all the bureaucracy out to a private insurer but the company is actually doing all the payouts. The quality of this coverage naturally varies from employer to employer. I once had a co-worker have a claim denied for an expensive psychiatric facility he sent his son to, but because he had the claim pre-approved he had grounds for a lawsuit. He had to sue both the insurance company and the company we worked for while working there.

The elderly have medicare, and the poor have medicaid, which are taxpayer funded but not always 100% coverage, and there's a bunch of private plans you can buy to fill in the gaps if you do desire with various pros/cons.

Our system is a complete fucking mess, although it's arguably still better than it was pre-Obamacare