I know a guy that got resuscitated because when he went from hospital to nursing home he keeled over faster than the nursing home could get his papers through the process and the staff didn't know he had a DNR. The family was pissed about that but he walked out himself a few months later. He wound up back at that nursing home and died there, but that was 7yr later. There's a balance to be struck. You don't want a DNR unless you're serious about dying.
My mother-in-law has a DNR. She was in Guatemala, got a kidney stone, went in for a CT scan, reacted badly to the dye, and her heart stopped. But in Guatemala, they don't know what a DNR is. The idea that anyone would actually want that is totally foreign to them. So they resuscitated her anyway. And, since it was just a reaction to the dye, she was fine - no adverse effects at all. And we're glad to still have her.
But she's also been a nurse, and has said that she didn't know anyone who lived past 80 who hadn't regretted it.
As someone who grew up in a medical family, my opinion is that most medical practitioners have a horribly warped view of aging. They spend their working life tending to the worst outcomes of age and end of life care. They think this makes them experts on aging, but really they remain experts on disease.
Plenty of people enjoy life past 80. I wouldn’t draw many of conclusions from your MIL at all.
My grandma is 84 and enjoying life still. Granted she can't walk as far as she used to, and gets tired more easily, but she's perfectly cogent and fun to have a conversation with. She's in a retirement village where she has friends with similar interests, and she even plays ping pong weekly. I won't lie, when I last played her a couple of years ago she could still take points off me. I don't think she regrets living past 80, though of course I would never ask.
My dad is 82. Up to a few weeks ago, he was going on his 3 mile daily walk, etc. He's getting better at playing bridge. He has a medical issue now but treatment may get him back to "full" activity (up to 4 or so years ago that was a 3 mile run, and that's probably off the table forever).
I don't know that he's enjoyed the past year because of COVID not letting him do very much at all, but if not for that, he'd have been golfing, etc, and scowling at the younger people driving carts instead of walking with their clubs :P. I think he has a decent life.
