Coup d’etats are most often

extremely peaceful.
very violent.
unsuccessful.
long lasting.

very violent.

A coup d'etats translates to "blow of the state" suggesting even in the language that it is a violent overthrow. Coup d'etats are typically violent and end with the death or imprisonment of the former leader if they are unable to escape. A coup is executed by the military or the elites of a society to remove a leader or to totally change the government system.

Examples of coup d'etats in history include Napoleon in France, Franco in Spain and Qaddafi in Libya.

i think it was because of how protected egyptian civilization was was which allowed them to evolve without much outside influence.