I don't think the Egyptians used magic, perhaps they knew a trick or two we don't know about, i don't think there's any writing left about the construction techniques.

The Egyptians' "trick" was massive amounts of human labor over a long timespan. Nothing you couldn't do a lot faster today if you were willing to spend the money (and manage to get the permits).

The construction of the pyramids is not impressive from a technological point of view, but perhaps from a logistical point of view.

It would cost something like $5 billion today and would take ~2,000 people ~5 years. Which is relatively speaking a lot less expensive. Put another way, Bill G could build ~17 of them in his lifetime and not be broke.

Awesome! What's at one time only the province of the greatest empire on the planet could become just one of many of a billionaire's projects. Let's scale this out from the present day with something of seemingly unattainable current value: How about The United States of America? Maybe several decades hence, a billionaire will have made himself the equivalent? Colonization of Mars, anyone?

Also, he's planning to spend your money on it, not his.

The point is that technology can be lost. Sure, we may have re-learned the technology in the intervening millennia, but we wouldn't have to re-learn it if it wasn't lost in the first place.