apart from being ill-suited to the profession itself, is there any other reason why somebody can fail eight ACs with numerous VI/telephone interviews...
A lot of folk have already given great advice here so there isn't a huge amount to add.
First off, I want to reiterate that you're faaar from the only person who's in this position, so please don't feel that you're isolated here. The other thing I'd say, as hard as it can be to hear, is that it's important to remember that you only need that one "yes" to really show everything you can do, so stay optimistic. The fact that you're consistently getting AC's is also a great sign.
From a constructive standpoint, generally post-AC rejections are (or at least can be) accompanied with some decent feedback. It's hard to say much on how to develop without more info as to what precise feedback you've been given - on that note, I totally understand if you feel uncomfortable sharing that in public as it might be highly personal, so feel free to DM me and I'll see if there's any further help I can give.