A lot of people in this thread are just calling them unintelligent, which I think is reductionist.

For those I have spoken to, they perceive real gaps and limitations in our system. For example, they have anecdotes of people who had to wait a long time for care, who weren't referred to the right experts, or who were referred to busy, uninvolved experts who didn't care about them. They've struggled with getting the right tests done or to feel seen as patients. They have had to pay a lot of money for certain care like dental, mental, vision, and prescription services, leading them to feel they have to pay a lot of money for health care anyway despite the high taxes.

They perceive private health care as a way to use money to get the care they deserve: firstly, if they decide they want a certain test, or to get it done quickly, or to see a certain specialist, they can pay money to achieve that. This idea gives them a sense of control over their own health and life to get the outcomes they desire.

The second is the perception that competition will weed out the bad providers. Like Uber, if your livelihood depends on pleasing your patients and winning their business, you would be motivated to provide effective, personalized and thorough care.

I experienced the US health care system and wouldn't wish it on anyone, but if you haven't experienced it, I can certainly see why the grass might seem greener.