In fact, the only reason such beliefs persist is mankind’s deep sense of romanticism and mankind’s even deeper sense of exploiting romanticism for profit. Books like Fingerprints of the Gods, The Orion Mystery, The Message of the Sphinx, and The Mayan Prophecies purporting such outlandish theories as ancient astronauts, Martian civilization, and Atlantis routinely outsell books on "hard" archaeology. So, as long as people want to believe the pyramids of Mexico and Egypt share a common source, they’ll be able to affirm their beliefs, at least to themselves, by charging $19.95 plus shipping and handling to their Visa, MasterCard, American Express, or Discover at Amazon.com.
Let's note that Native cultures built mounds, which are a kind of primitive pyramid, all over the South and Midwest. Were they all influenced by Egyptians? Or is raising oneself above the ground, reaching for the heavens, a natural inclination of people everywhere?