Nobody is being euthanized due to a lack of "basic" health care. There are a small subset of people with significant health challenges that are choosing to die instead of wait for the advanced care they require which can often take years depending on how specialized it is and complicating factors. The vast majority of people who opt for this have terminal or untreatable conditions, only a small number of people choose it when care is actually possible but just delayed.

In the US, those people could get care if they were wealthy. Unfortunately for the vast majority of Americans they aren't wealthy enough to pay for advanced specialized care, and the US poor don't even have the option to wait for it, they just get to suffer or die directly.

At least our system gives everyone a chance.

Also the costs involved in medical assistance in dying are orders of magnitude smaller than the cost of the care these people need. It's a handful of doctors visits and a pill/injection to die, versus needing multiple visits with specialists, followed by surgery (or sometimes multiple surgeries), massive drug regimens, all followed with physio and other rehabilitation.

Would I like these people to always have the care they need right away? Sure.

Am I willing to significantly increase my taxes just to provide a stupid amount of medical care to everyone? No

There have to be reasonable limits to healthcare spending or we could spend every single tax dollar on more healthcare and still not be able to provide every single procedure to everyone with no wait. There are wealthy people who spend millions of dollars a year on their healthcare, and that's just not realistic to give to provide to everyone.