Why do all the men on the Egyptian national soccer team play for Egyptian clubs?

Ofcourse going international is every player's dream, simply because of the new experience and the world wide recognition...But again the egyptian league is not at all bad, but i know of some egyptian players who play abroad...Ahmed El Muhammady plays for Sunderland the english club, Mohammed zidane (zizou) plays for Dortmund in germany, Doody el Gabbas plays for belgium...there are also others who play in other non-european countries, like Mohammed al Hadary, the best egyptian goalkeeper,who plays for sudan, and Ahmed ali, who plays for al Hilal in saudi arabia