You bring certitude to a subject where certitude does not exist. Now, if you would care to spell out word for word what is written in all those hieroglyphics, feel free. But don’t adopt the audacity to assert everyone knows how and why the great pyramids were built, because even experts in hieroglyphics disagree on their meaning. By the way, I doubt they were built by Joseph for grain storage, but find it distasteful to mock someone who holds to that theory.
Not much room for grain storage inside.
Also, they took 30 years to build. Can you imagine spending 30 years on a food storage unit?
Also, can you imagine a non-Pharaoh commanding the resources necessary to build them?