There are these people called Egyptologist who spend all their time studying ancient Egypt. These are the guys who actually dig up artifacts, sort through information, or read the hieroglyphs. The knowledge that these guys have gathered is the accumulation of the work of many people over hundreds of years. No one person makes sweeping discoveries that change everything over night. Even big discoveries like King Tut's Tomb take time to sort out. They also are subject to peer review. One person might make a claim but someone else disagrees and they argue about it. A concensus could be reached, or there will be different schools of thought.
People who call in to late night talk shows, or do specials on TV claiming that all the Egyptologist who ever lived and worked are wrong and that they know all the answers need to do their homework. Someone who has never lifted a shovel in his life needs to go to a library and read about Egypt, learn what the Egyptologist think and how they arrived at their ideas before advancing any theories that will rewrite the history books. He needs to publish his ideas, let other scrutinize them and critique, argue with those people, and support his points with verifiable facts.
Would you go to the doctor and tell him that all medical science since hypocrates is wrong and that you and you alone have somehow come upon the real knowledge of how to cure your diseases?
And actually the history books have been rewritten, if you find a text from 20 years ago and compare it with one today you'll see a lot of differences.
I have gotten warmed up, but I'll end it here for now so as not to go too long. I'm ready to do a tirade about the pyramids and the baloney that surrounds them in a later blog.