The Egyptians were preoccupied with continuity and permanence, because they obsessed over the afterlife and their religion.
Their strong religious beliefs made the kings as close to god-like as a human could be. They believed that if they made a perfect burial tomb, they were more god-like. They believed that if they built a tomb symmetrical, they were essentially setting the stage for a perfect afterlife. In the same way that believing that if they brought all of their riches with them to be buried, they believed that having a “perfect” tomb would help ensure their afterlife.
They believed that they had to build these tombs to be permanent, because they would return to them in the afterlife. Because they believed they were gods, they had to build these tombs to be extravagant and structurally sound so that they had somewhere to return when they came back in their afterlife.