Well, I suppose that since I have never been to Egypt and don't have the material equipment to measure the amount of carbon-14 in mummy wrapping or something, I suppose that no, I don't know with complete certainty how old Ancient Egyptian civilization actually is, or if it even existed. Mind you, even if I could go to Egypt and personally use radiometric dating on mummy wrapping, I still wouldn't claim to know anything about Ancient Egypt with 100% certainty. I don't claim to know anything with 100% certainty. However, I can say I'm pretty sure that Ancient Egypt existed and that there were people living in Ancient Egypt before 2400 BC.
And yes, I am relying on the authority of others. I might not be able to go to Egypt and perform tests to see how old anything is myself, but I can read about others that have done so, what methods they used, how those methods work, what the error margins of those methods are, etc. I can see what other people who have conducted similar studies think. I might be forced to rely on authority, but I can also understand how these authorities arrived at their conclusions and within what margins of error.
If you are going to contend that the research of hundreds of experts is incompetent and inaccurate, I expect you to provide evidence as to why you believe this. Show me what they did that was incompetent and how your findings differ. You don't just get to assert things.
Why should I trust you, Robert Byers, over all those experts who have spent years studying to become experts, spent years working in the field, have published their findings, and made them open to the ruthless scrutiny of their peers?