At this point I would be mildly surprised (though pleased) to discover that there was any metaphysically significant "reality fluid," mostly because it seems that even in a universe without any everyone would have all of the same evidence for its existence that we do.

Is it a trivial mistake that I am thinking of quantum amplitudes as a sort of "magical reality fluid"? Isn't something like that needed for an explanation of why we live in a world where all our measurements seem to have followed the modulus squared law with respect to this number?