If you make $50,000 per year in the US, which is the median full-time wage, your healthcare is almost entirely paid for by your job. The top 1/3 earns far more than that, they have extremely good coverage and extremely fast access to healthcare - along with easy access to the world's best medical technology and drugs - that is superior to comparable systems in Canada and the UK. The top 1/3 in the US do not suffer from rationed care, as other systems do. That top 1/3 has access to elite doctors, and elite hospitals. That top 1/3 is the wealthiest large group of people on earth, in basically every regard.

That top 1/3 has absolutely no interest in changing the status quo until it no longer works for them.

The elderly in the US also do not want the system changed. In France, Canada, the UK, and many other similar nations old people have highly rationed care access. Whereas in the US, old people drain an immense share of healthcare resources, far out of proportion to comparable nations. Old people in the US are a large voting block, and a rather powerful influence group (AARP etc) in terms of lobbying to keep what they have.

The bottom 1/5 gets free healthcare, and it's OK. In the US, it's primarily the next 20% above the bottom 20%, that suffers when it comes to the existing system (they make enough money from time to time to fall on and off free healthcare, they're trapped in healthcare hell frequently, and they make up a large percentage of the people that declare medical bankruptcies every year).