If someone is dying you can in theory use machines to replace the function of most of their major organs and keep them alive a bit longer. This costs a lot of money and for a lot of elderly people it will just mean they suffer for longer before dying anyways. There are ethical rules in place for when and for how long machines should be used.

Idiots call the people who drafted those rules a death panel but in reality if you are filthy rich you can always ship your broken dying body somewhere people are willing to keep you alive a bit longer for stacks of cash, the free medical system in countries like canada doesn't prevent you from spending your own money on healthcare elsewhere.

The reality is that overall people recieved better care for a lower cost under single payer health systems like Canada/UK.

It may not be politically feasible to pass legislation but Bernie is 100% correct that the USA should move to a free single payer health system like Canada and most of Europe has.