To say that all is
in consciousness does not mean that all is
conscious, which is a point further elaborated upon in the book. Idealism does
not say that the sun is conscious, in the sense of having private inner life and intentionality like you and me. It only says that there is nothing to the sun but what is experienced 'somewhere' in consciousness (not necessarily your personal consciousness alone). See:
http://www.bernardokastrup.com/2014/07/ripples-and-whirlpools.html and
http://www.bernardokastrup.com/2015/04/the-reality-nervous-system.html (point 3).
Now, idealism does say that the universe
as a whole is the external aspect -- the outside image -- of some kind of 'cosmic' conscious inner life, in the same way that your body-brain is the external aspect of your conscious inner life. But that does not necessarily mean that the universe's inner life is anything like yours or mine, with the potential for agendas, whimsical preferences, deception, etc. Indeed, idealism doesn't deny that many aspects of reality unfold according to strict patterns and regularities that can be modeled through stable 'laws.' It only says that those patterns and regularities exist only insofar as they are experienced 'somewhere' in consciousness. As such, this 'cosmic inner life' of the universe as a whole may unfold according to strict patterns and regularities akin to what Jung called archetypes. It isn't necessarily self-reflective or premeditated (in fact, I think it isn't), but rather instinctive.
As such, it is indeed a bit myopic to ask why the universe is deceiving us by pretending materialism to be correct. That some people's
interpretation of the universe is wrong no evidence of a deception on the part of the universe, for exactly the same reason that our earlier misinterpretation of the behavior of the sun was no evidence for a deception on the part of the sun. The universe is simply what it is. How we interpret it is our own responsibility, not the universe's.