Definitely agree. I had been slowly deteriorating since I was about 6, and then everything caught up to me and I started to deteriorate pretty rapidly around 22. It definitely is scary. I'm not even 30 yet, but just based on how my whole life has gone, I know that it's only going to get worse as time goes on. I'd much rather live a long, happy and healthy life, and I've grieved the idea of that for an extremely long time, but realistically that's just nowhere in the cards for me, and I'm doing myself absolutely no favours by keeping this going any longer.
I've always been afraid of getting old as well, and I think that, even if I weren't so buggered up in every way imaginable, I still wouldn't want to live into old age, but it's hard to say for sure, because I've just... always felt that way. I'm already jaded, in constant pain, dependent on others for help, etc, and if I even were to make it into old age exactly as I am right now (which I can't even fathom), everything that comes with old age on top of all the issues I've already got would just be the icing on the shit cake. Hard pass.