Egyptians didn't build the original pyramids, so why should we be able to do it? We won't be able to build another Stonehenge or Göbekli Tepe or even Baalbek, I guess. Heck, Egyptians didn't even build the Sphinx.
Who did? Aliens?
The pyramids aren't actually that old, they were built during the British period in the 1890s as a means of disposing of spoil from their quarrying operations. Really they're something of an eyesore.