A literal answer to your question is at the root of most mental symptoms: we are, in the regressed state, RELIVING the experience a thousand times a day, reliving the original memory/moment of FEELING the sudden AWARENESS of the DP.
It's not that we are observing "oh, my....that Self that vanished is still gone, yep, sure is..."
We are re-experiencing the precise same moment over and over of "what is HAPPENING?:!" as if it was all happening again FOR THE FIRST TIME.
Intellectually, we know we have been Dp-ridden for "x" amount of time. But viscerally, emotionally, REGRESSIVELY, we FEEL it as if we are just this instant experiencing it.
That is precisely why we cannot ever "get used to it" the way even a severely crippled person, or even a blind person, makse SOME level of adaptation and acceptance and no longer feels every single day "OH, MY GOD, I'm BLIND!" Yet, we do. Every.........single..........day, we are re-living the moment of the traumatic awareness of self as purely subjective and fragile.
Over
and
over
and
over
and over
That's why Logic doesn't help. And time/experience never makes it any easier. That's why we keep saying "but my Lord, I have already had this kind of bad episode a THOUSAND times in my life, why do I still feel like running down the hall, screaming that I'm losing my mind?!"
THIS time, this very moment of fear, is the ONLY moment of fear in regressed states. We feel like every other time was nothing compared to this, only a "trial run" and THIS ONE is the BIG ONE where we finally "go insane, die, run bezerk, do something awful, lose contact forever, etc. etc."
Mental symptoms in regressive psychological states are a re-living of a single moment of pain/terror as if it is happening for the first time.
That is partly why you will never MASTER it directly, or "figure it out" or "Talk yourself out of it" - only by pushing in the other direction can you allow your mind to stop re-instituting the original experience.
