This is my soapbox issue. Afox has already said a lot of this...
TLDR: Educate yourself. Know your coverage.
Most medical bankruptcies are caused when people get sick and then lose their jobs. They then also lose their health insurance that was tied to their jobs. Another cause is people who have high deductible and OOP maximums and no ability to pay them. Imagine you make $15 an hour and have a $4000 deductible. Those bills will just pile up, year after year.
However, we are FIRE folk, so neither of those issues apply to us. Our health insurance will not be tied to our jobs (retired), and we have saved for this (deductibles,etc.). For us the risk is in needing what’s not covered. So you need to know what’s not covered.
Out-of-network is the biggest risk. (1.) What hospital is an ambulance going to take you to in an emergency? Is it in your network? If that hospital is not, you need a different health plan. (2.) If you get cancer, where are you going for treatment? If those providers are not in your network, who is? If you aren’t happy with that, you need a different health plan. (3.) Are there any other doctors or hospitals you want access to if you get sick?
Next up is prescription drugs. All the insurance companies have their own rules about drugs - how many, how often, what requires pre-approval, what requires step therapy, what copay tier, etc.. You need to know how to access this information. If you take an expensive drug, and it’s not on your health plan formulary in a preferred tier, you need a different health plan.
Some things are just not covered. If you have dental, it’s only going to pay $1-2k per year maximum. Vision plans don’t pay out much more than you pay them. Hearing aids are rarely covered and cost thousands.
Does this mean you can’t retire? No. You could work, get sick, lose your job, and be in the same place.
The health insurance plan matters. I worked for several in my career. I live in a state with several that are good. Avoid for-profit plans. I would NEVER enroll in a United Healthcare plan.
Grievances and appeals work. And if they don’t, be the squeaky wheel. Send letters to the CEO of the company. File complaints with your state insurance office. Send letters to your Congressperson. I have seen firsthand how well these work.
Lastly, Medicare does not solve these problems. It has deductibles and coinsurance and does not even have an out-of-pocket maximum. It doesn't cover dental, vision, or hearing. You still pay 5% of all drug costs, even in catastrophic phase.