We sometimes say of someone we consider arrogant, "he thinks the world revolves around him", and thus formulated, we can see clearly the error of perspective.
But it is an instinctive, explicable perspective - the evolutionary advantage is obvious - things happen to us or not to us; they affect us directly or indirectly or not at all.
'We' 'live' 'our' 'lives' entirely in the eye of such concepts!
Existentialism takes our individual existence, the individuality of our existence, as a given, indeed as the given.
We are here, we are ourselves... what next?
The key issue is perspective: assuming the right of perspective.
The right to perspective is not contingent upon the ability or even the potential to perceive, but it is in the nature of that ability that it prioritises itself.