We would think of them principally as a mnemonic to rememnber the dead king during the day and the star to which he ascended as a mnemonic to remember him (and his place in history) at night.

But they were far more and it was the "practical" reasons that caused them to become a pyramid building society.

They were mostly infrastructure and used for food processing and canning. They also had industrial purposes.
The Great Pyramid itself is a time capsule.