FWIW, I have an invisible disability. I care for my DM who has cerebral palsy - I've been a carer for her for my entire life as she was a single parent and it was just me looking after her when I was just a child myself. My two DC (twins) were born very prematurely and have (different) disabilities and will never live independently. My DP collapsed at work three years ago with a previously unknown neurological condition and can't ever work again. Until 2012 I was the sole carer for my DF who had Huntingdon's Disease. I was with him single-handed until he died.
My whole life has been spent around a whole host of disabilities, and still is. I unfortunately am only too aware of the limitations that the NHS has and what it's like living with chronic disabilities.
You can get as cross and sweary with me as you want. It doesn't make what I said untrue. Or unkind. I said it as gently as I could, and made it clear that I wasn't criticising.
The point I was making is that what would someone do in your position if they weren't able to access private treatment? Many, many people wouldn't be able to afford it. That's why it's not "essential". That is why it's a choice.
I didn't say it wasn't a good choice.
And I didn't say that it won't make a huge difference to your life.
I acknowledged that in my previous post.
OF COURSE if you can afford a treatment that will make a fundamental difference to your quality of life and prevent your condition from worsening, then it's absolutely understandable why you'd pull out all the stops to do it.
But not everyone is able to because they simply don't have access to any money that enables them to pay for private healthcare, especially if they're disabled. That's why it IS a choice, whether you're willing to concede that or not.
It sounds as if you're putting the money to good use and it will make a genuine difference. Your family member sounds as if they want to be fair, even if the money won't be appreciated by others. I don't think you can fault them for that.