My own experience with covid that almost involved a death thankfully didn't thanks to the extensive medical knowledge of the family. They brought the grandfather to the ER with covid and he was at 92 % blood oxygen. They wanted to ventilate him but the family refused and asked for oxygen instead. The ER waited for over an hour before the family complained and he received a nasal cannula with oxygen. He was fine within 30 minutes. I do believe the family's action prevented his death.
I think it wasn't just covid that was the problem so much as there was a lot unknown about it that was the issue. No idea how to treat it and the relying on ventilators. Covid is a respiratory disease and one of the key risks of being placed on a ventilator is the development of pneumonia:
https://www.nhlbi.nih.gov/health/ventilator/risks
Pneumonia in itself is deadly and combined with covid symptoms I'm sure that didn't help. The upside of all of this is we now have a better understanding of how to treat the thing. I just pray we can all be kinder to one another