Why would a universe need anybody in it?
A universe needs something in it that keeps records, because consistency is a property of descriptions, and a description has to be held by something. Where nothing keeps a record, nothing can be right or wrong about anything, and the structure fails the test for existing at all. A thermostat is enough for that first step. It senses one part of the world, holds a number, and throws a switch when the two disagree. The thermometer beside it fails, because nothing consults its mercury. Simple native observers keep the physical layer in place, yet the universe needs more. It exists only if it closes on itself, and closing takes observers intelligent enough to recover its law from their records and build the screen that computes it. That is why life and intelligence must evolve. Putting observers first gives them no power over the world. Observers get what they can consistently record, and every result follows from that limit.
Also in Chapter 2: Why Is There Anything Rather Than Nothing?.
This answer comes from OPH, Observer Patch Holography. OPH is a rigorous, consistent and complete description of the unified, self-creating computational Universe we inhabit. Its consistency is machine-checked: the fixed point at its core is constructed explicitly, and a theory with a model contains no contradiction.
To understand OPH and check every step yourself, start with the free book Reverse Engineering Reality. It builds the theory from the ground up, and the OPH Notebook answers your questions while you read.
read the free bookask the notebookor ask sage:read chapter 3: Why Would a Universe Need Anybody In It?watch a universe make its own particles