I think you’ve misread things again. People do ten days isolation because that’s how quickly it usually takes to go away; if you’ve still got symptoms after ten days that’s when they said you should seek medical advice.
If the advice is go to hospital, it’s then that they get treated and assessed and only then (when that’s not worked) that they’d go on ventilators and so on until the end. This can happen quickly but is more often several days / weeks.
This is something that’s clearly seen in both previous lockdowns so I don’t understand how it’s difficult to grasp.
I don't think that's actually true. They say 10 days is the time you could be infectious isn't it?
If you have severe/bad symptoms from COVID for more than 6-7 days mate that's when you should probably seek help.
I'm going off my experience, the experience of my sister and brother-in-law (who were unvaccinated at the time), my dad, my friends.
None of us had symptoms (or even kept testing positive) for longer than a week. My sister and brother-in-law had worse after-effects, definitely, but they weren't ill. Same with me, 5 days of illness (6 days of testing positive, though I could well have been positive before I did test as as I've said before I was feeling fine and had no reason to test until I did one to go to work).
Same with my friends, 5-6 days of illness (for those who got ill - one of them was just 3 days but he had very, very mild symptoms). The only people I know of personally who have ended up in hospital due to COVID, have been really bad for going on past a week. Two of them sadly died (my dad's cousin and my mate's granddad, another was someone my age who ended up on Oxygen, had asthma but fortunately he's fine now)
If you're healthy and/or vaccinated, you aren't going to be ill for 10 days and if you get near that at all you should be going to hospital.