This has nothing to do with the football. It has everything to do with the political reality of Egypt and the tribal systems that have been transported into the fanbase of sports teams.
Violence between fans, players and fans and players is not that uncommon in most sports. Deaths on the other hand is rare, but we are talking about the biggest sport on the planet. Sure 50+ people died at a sport stadium, but considering that millions went to stadiums world wide yesterday alone then frankly it is a one off. More people die going to and from the sports arena than are killed at sport arenas.