The US's healthcare is worst among industrialized nations (not "in the world") because of the lack of free medical care. People here wait until they're really sick before they go to the doctor or hospital to have a problem investigated,
You were so close. The US' healthcare is worst among industrialized nations because of the nature of our free health care. Only emergency services have been free until now. That is what leads to the situation you describe. If there were no free health care here you'd have what we had before we made ER visits free for people with no money. Well, you can still be charged and such, but so far you can't be imprisoned for failing to pay.
Like so many of our institutions, it seems designed to maintain the populace in a state of poverty. Most of our entitlement programs are like that. If you start to save money to get yourself out of your situation, you won't be eligible for assistance any longer. That's why poverty is a trap. Even worse, it is functionally illegal to be poor in the USA. It's functionally illegal to be homeless. Some people up in my corner of the world have made the BLM land their home, and they just sorta roam around shooting pigs, which are always in season because they are a sort of plague. They cause damage to basically everything; crops, livestock, whole ecosystems as they root around killing plants, increasing erosion. Unfortunately, the shutdown meant a lot of people kicked off of those properties, which supposedly belong to all of us...
Also, for-profit & pseudo-"non-profit" hospitals cut corners to the very edge of endangering patient care -- having far more patients per nurse than is wise, relying too heavily on student nurses and LVNs, having them work extra-long hours, nurse practitioners taking the place of doctors for stuff beyond vaccines & standard mild illness, and so forth.
The biggest problem in medicine is capitalism. Charging whatever the market will bear, in this case, means endangering the health of everyone below the baseline.