Reality as we think of it is actually a hologram. Even science is now confirming this. So I want to put this into a context which is simple enough to understand. If you want to know about the physics of this, there are plenty of youtube vids to watch. An important consideration is what Marshall McCluhan quote “The Medium is the Message”. Since the media through which we analyse the Universe have become more advanced, so have the experiments which we’ve been able to conduct. The computer is probably the best medium and metaphor we currently have to understand the nature of things. But of course, it all boils down to language; “In the beginning there was the word”. Virtual reality, matrix, hologram, holo-deck (from Star Trek); these are all terms which are being employed, but hologram is probably the most common, so let’s look at the origins of the word:

Holo:
before vowels, hol-, word-forming element meaning “whole, entire, complete,” from Gk. holo-, comb. form of holos “whole, entire, complete,” also “safe and sound,” from PIE *sol-wo-, from root *sol- (see safe (adj.)).

Gram:
metric unit of weight,” 1797, from Fr. gramme (18c.), from L.L. gramma “small weight,” from Gk. gramma “small weight,” originally “letter of the alphabet,” from stem of graphein “to draw, write” (see -graphy).

And now let’s compare it to UniThou:

Uni:
word-forming element meaning “having one only,” from L. uni-, comb. form of unus (see one).

Thou:
Pronoun: (archaic, literary, or dialectal) ‘you’ singular informal, nominative case
verb: (transitive) To address (a person) using the pronoun thou, especially as an expression of familiarity or contempt

So in hologram we have the whole, and the small unit, and in UniThou, we have the One (implying unity), and the singular familiar (implying the separate individual).

Nowhere, though, do we find any reference to ‘illusion’.
All that’s changed is the conception of reality as being ‘out there’ to instead, actually coming from within and being projected outwards onto a kind of ‘screen’ . Just like a film projector onto a movie screen. A unified field, which when we aren’t perceiving it is kind of a formless ‘soup’ of potential, becomes a 3D reality when we do perceive it, as if it were doing a specific kind of dance for each of the senses, or a kind of improvisational theatre (it being both the stage and the actors), in order to experience itself subjectively.

The danger when we consider a unsubstantial reality is the fear that can come about when we consider that we don’t exist. What it really means is that the unified field of formlessness is unfolding through us. To then ask ‘why’ is just like asking an artist why she paints, or an inventor why he invents. The uniqueness and novelty of each individual’s (thou’s) experience of the ‘holo’ or the ‘Uni’ through the mythic phases of life.