Well, it's still a fun Fermi calculation problem, anyway.

Let's see, the Pyramids have been the targets of tourism since at least the original catalogue of wonders of the ancient world, Antipater of Sidon ~140 BC which includes "the great man-made mountains of the lofty pyramids". So that's ~2150 years of tourism (2012+140). Quickly checking, Wikipedia says 12.8 million people visited Egypt for tourism in 2008, but surely not all of them visited the pyramids? Let's halve it to 6 million.

Let's pretend Egyptian tourism followed a linear growth betwe... (read more)