1) The guide will fight off a lot of the annoying, aggressive, vendors that would come at you like flies to honey.
Lepton has mentioned this in her trip notes that they are very grateful to have a guide in Cairo.
2) The guide can explain the sights and help us better understand / appreciate on what we see. From what I read, guides in Egypt are regulated, they are supposedly have to pass certain degree of knowledge test on Egyptology stuff. Unless you have very very good knowledge on Ancient Egypt history, all those dynasties, etc etc, otherwise I think having a guide to explain things is very helpful.
We know we would want / need a guide in Egypt although we have never had a guide in all our trips up to this upcoming one.
Why dont you use the WeChat contact contact to find your bargain cruise?