Egyptians considered immortality the key to reach full god-like characteristics that would enable them to have complete permanence in Earth forever. They believed that the afterlife was the only way to come back to their world. As of this, the creations of the tomb pyramids and the mummification established the opportunity for the Egyptians to find their way back to their world and treasures.
The monuments that stand today in Egypt show how much importance the Egyptians gave to continuity and permanence. All the years and money they spent to create these enormous tombs, represent what the Egyptians though was most important to them. Likewise, their strong effort to create these vast tombs with the company of unique treasures, showed the magnitude of all the pleasures and accommodations Egyptian rulers created to live like gods. By creating such accommodation and pleasure, it is understandable why the Egyptians built those vast pyramids; who wouldn't like to go back to those accommodations that enabled them to live a life filled with pleasure and power?
The only ones that had full reach to acquire the afterlife, however, were the pharoahs along with their families. Only they, had the absolute wealth and power to create a path to immortality. Furthermore, since a pharoah was believed to be a god, the buildings of the pyramids would stand as evidence of how much power and wealth they had as rulers over Egypt.
Overall, Egyptians used this belief to rule over their people, to be remembered, and also to find their way back to what they were given, for having the power of a royal ruler.