They definitely are tombs. There’s a linear progression of burial practices with a direct correlation of protection from grave robbers. First, there were grave pit burials in the Predynastic period. These were easily dug up and robbed so they decided to build structures around the grave itself, called a mastaba. During the Old Kingdom, King Djoser build a large mastaba and then decided to add on to it, which is the Step Pyramid. King Snefru saw a new vision with this monument and wanted to make one with straight sides. His Meidum Pyramid was the first attempt but it didn’t work and the outer stones collapsed. He tried again with the Bent Pyramid. Halfway through the project, they realized that the angle was too high and would create too much weight. Fearing collapse, they changed the angle, giving it an awkward look. He was determined to build a true pyramid and finally did with the Red Pyramid, using the corrected angle. His predecessors (Khufu, Khafre and Menkaure) continued the tradition and built the best pyramids. King Unas then included pyramid texts inside his burial chamber. These texts refer to guiding the pharaoh in safe passage in the afterlife.

The decline in pyramid building occurred as the end of the Old Kingdom entered into the First Intermediate Period. Egypt (and Mesopotamia) were dealing with severe droughts, which leads to famine, whoch leads to social unrest, which leads to a decrease in the faith of the pharaoh. On top of the environmental and social crisis, the pyramid building projects were way too expensive and nearly bankrupted the economy when the projects ended. On top of that, the reign of Pepi II was the longest in history. By the time of his death, he had multiple sons, grandsons and great grandsons competing for power, leading to civil wars. So with climatic disasters, economic decline, fragmented nation, social unrest, government failures, etc., Egypt didn’t have the ability or need to build great monuments. This is why tombs of rival kings during the First Intermediate Period are rock cut tombs, not pyramids. When the country came out of the dark age and the Middle Kingdom arose, they started building pyramids again. But this time, they learned their lesson. They knew that they could not build with such scale and grandeur again. Making pyramids out of mud brick instead of stone is cheaper, faster and easier. That’s why Middle Kingdom pyramids are mostly piles of rubble today and the public barely knows about them. Another interesting things is that instead of pyramid texts, they began inscribing texts in coffins themselves. All of these pyramid complexes come with mortuary temples nearby, which are cult centers for mourners to give offerings to the dead kings. And most of these pyramids are also surrounded by cemeteries of elite people.

Another dark age occurred because of the foreign invasion of the Hyksos. When the New Kingdom arose out of the Second Intermediate Period, the kings knew that all the earlier tombs had been robbed. During times of strife, people get desperate enough to loot royal tombs. And since pyramids are giant billboards that say, “hey I’m full of treasure”, the New Kingdom pharaohs decided to hide their tombs in a secret places called the Valley of the Kings. Unfortunately for them, they were all robbed too during a Third Intermediate Period. Hundreds of years later, the Kushite kings wanted to reignite the Old Kingdom ideas and began building pyramids again. This time, they were much, much smaller. The reason being is that they built in modern-day Sudan, where there is less stone resources and also the Nubian kings didn’t have the power or wealth to build on a larger scale.

There are over 100 pyramids in North Africa and all have been known to be tombs for millenia, even by multiple ancient historians like Herodotus, Menetho, etc. Only in recent years, when misinformation is so easily promoted through media and politics have people questioned their purpose. It’s sad that something so obvious is so debated by the most ignorant.