It's the "god" part of "god king" that was the delusion, and all of the wasted effort that went into ensuring the Pharoah's resurrection and immortality after death. And yes, it's a delusion regardless of how many people believe in it.
If we all have the delision that you can fly with the power of your mind that is still a delusion. Because one can perform an experiment and see that you in fact can’t fly with the power of your mind.
But if we all believe that you are the eastern bunny, or the coolest dude on the planet, or the twice crowned poet laurate, those are social constructs. We believe you are the eastern bunny and that makes you the eastern bunny, and that’s no longer a delusion.
I think your hang up is that you have a set of expectations you think a “god” should fulfill, and clearly the pharao did not fulfill them. And that is an objective fact. But there is no reason to expect that the ancient Egyptians shared your expectations about what a god is.
> ensuring the Pharoah's resurrection and immortality after death
That does not sound correct. I don’t think they believed that the Pharao will walk again after he died. That is what the world “resurection” would imply. Their belief was that there is some form of afterlife where you need to perform certain rituals. The pyramids and the treasures were there to aid the pharao in peforming those rituals so he can obtain a better position in the afterlife.
"I tell you, Winston, that reality is not external. Reality exists in the human mind, and nowhere else. Not in the individual mind, which can make mistakes, and in any case soon perishes: only in the mind of the Party, which is collective and immortal. Whatever the Party holds to be the truth, is truth. It is impossible to see reality except by looking through the eyes of the Party."
We like to think everyone was dumb but I'm pretty sure if those dudes could build pyramids, a lot of them also knew the Pharaoh wasn't a God even if lots of people believed, same as today with religions or cult of personality leaders.
The Pharaoh wasn't a god, it was a ruler. I think they had the sun and other elements as "God". Kinda makes sense to praise the sun as it makes their agriculture go.