Another notorious case (actually many cases) in which hypoxia causes death is among climbers on Mt. Everest. Some of the most egregious deaths involve experienced climbers, including professional guides, committing acts that are entirely against their own better judgment.
I suffered an hypoxic incident when standing in a queue, indoors in a shop, and masked. I didn’t realise what was happening at the time and only figured it out several hours later when I was back to normal. I have chronic rhinitis which means my airways are partially blocked all the time. It sometimes makes it difficult to get to sleep. What it is like when you have a bad cold and your nose is blocked.
The trouble with hypoxia is that it comes on suddenly, you don’t know it is happening and the first thing to go is your critical faculty. You lose judgement. Your focus can narrow to such an extent you fail to register danger. One moment you are normal. The next moment with no sense of transition it is like you are extremely intoxicated.
The advice that masks are no danger because you can always take them off does not work – you don’t think to take your mask off because you don’t realise at the time that something is wrong.
Recently a postman was reported leaving an elderly woman having fallen (dizzy due to having had the Covid vaccination the previous day) lying on her doorstep, unable to get up, in the snow in freezing temperatures. This lack of judgement, even in life threatening conditions, is typical of someone affected by hypoxia. I notice he was wearing a mask, and his comment – his vague mumble suggests he was away with the fairies.