The Egyptians only do well on the campaign map because they have no real enemies apart from the Selucids, who as we know are surrounded by enemies.

Guarding their flank they have the Numidians in Lybya, but any invasion force travelling into Egypt that way is going to take a very long time to get there because Lybya is such a massive province... With its city closer to Egypt than it is to the other side.

On the other side we have numerous rebels, who are easy pickings for bribery and invasion... So no threat there.

The only real challenge to Egypt are the Selucids, but they are in a real tight spot having to contend with Armenia, Parthia, Pontus, and the Greeks, so they never really manage to get off the ground before they are assaulted from all sides and massively weakened.

Also once Egypt really builds up its core provinces around the middle east, it becomes very self-sufficient in trade and can make a lot of money just by trade between its cities in the Middle East... From what I can see no other faction can make as much money unless they control that area or more territory.

Egypt does well because it is rich and has no real tough enemies early on. The Selucids cannot contain them and the other factions around them are too busy fighting amongst themselves to worry about Egypt until it gets too big.

Oh and for those of you who are worried about Chariots, here's one way to deal with them: Bedouin Mercs!!