Why do so many people live in Cairo?

Egypt is a very central country so all the services and important issues are centralized in Cairo, and hence, anyone who wants to have a real career or acquire more knowledge or have a better standard of living has to go to Cairo Egypt has a population of 80,000,000. Cairo has 20,000,000 i.e. 25%! The area of Cairo is less than 1% of Egypt! so 25% of the country is living over less than 1%!! Mohaly.blogspot.com