how do you define "cannot afford"?

no fund in bank account, no institute willing to make you credit ?

suppose i have 1k/month extra income. my options are:
1) pay 1k/month towards meds and break even
2) pay 1k/month towards a new luxury car / house and have the gov pay for my meds

i'll take door #2

..it's not my decision whether they live or die .

Yes, socialized health-care systems do this by rationing care, market oriented solution do it by price.

1) cure population
2) let die population but cure yourself and have a new car

murica !!!

in 2009 45,000 americans died every year from lack of access to medical care because they didn't have health insurance
http://www.reuters.com/article/2009/09/18/us-usa-healthcare-deaths-idUSTRE58G6W520090918

despite the image portrayed by conservative mythology, canadians are not dying in large numbers on waiting lists by comparison
https://www.fraserinstitute.org/uploadedFiles/fraser-ca/Content/research-news/research/publications/effect-of-wait-times-on-mortality-in-canada.pdf

the general impression i get isn't that canadians with life-threatening conditions will stay on the wait list too long but that canadians who have non-life threatening conditions will. things like Laparoscopic cholecystectomy (gall bladder removal surgery) make your life significantly better but it's not terminal if you dont get it.

If someone has lived beyond their means, and not saved a penny for retirement, does society have an obligation to provide that person with anything beyond basic sustenance?

not always, if you happen to have a non-life threatening problem you may wait many months if the professionals for that specific treatment is over booked. Even then you can go private if you can afford it.

So yes, if you are poor + non life treating problem + over booked professionals for that specific treatment + not willing to wait because don't like the inconfort, then yes you can rage about Canadian health care system