Uh..no..I'm not sure where you're getting your facts but no this is completely false. Most Americans have either Medicare/Medicaid, or various levels of employer sponsored healthcare, most of which are really poor or push large burdens on their employees. I have fully paid for healthcare through my employer and I STILL have a $5000 max out of pocket that I have to cover before insurance fully covers me. To put that in perspective that's an entire month's income in a country where most people live paycheck to paycheck.
Oh and the cherry on top of that is that in the US you can literally be fired for getting a prolonged medical illness, such as, oh say, cancer, which impacts nearly every single American. It's totally legal, which then takes your wonderful healthcare and removes it right when you need it most and can least afford to lose it. Another fun fact is that it's really hard for most people to work when getting prolonged medical care, which means, again you can't really pay for the bills you are getting.
If you think quality is great, then you're lucky. US hospitals can flat out refuse to treat you properly if you're "lucky" enough to go to a Christian based hospital, which will deny care unless life threatening, in some states this nears the majority of hospitals.
So no, most people who go bankrupt from medical bills in America HAVE health insurance. You're living in a fantasy bubble I suggest you step out of before you get a huge shock. I sincerely hope you never have to experience this first hand because it's absolutely hell for those who have to go through it.
Sources:
Average US Income: https://en.wikipedia.org/wiki/Household_income_in_the_United...
Catholic Healthcare: https://www.forbes.com/sites/judystone/2016/05/07/health-car...
Healthcare bankruptcies:
https://www.cnbc.com/id/100840148
Rebuttal: https://www.snopes.com/fact-check/643000-bankruptcies-in-the...
https://www.studyfinds.org/two-thirds-of-all-american-bankru...
Edit:
I don't mean to suggest US healthcare providers are poor, it's generally the best in the world if you live in the east coast, Texas, or west coast the south and midwest generally have poorer coverage with the exception of cities. We basically have the best healthcare that you can afford, the problem is that most people can't afford it.