Caesar Nero offical title written in Hebrew =nrwn qsr
which if added together equals 666. Nero was contemporary with the writing of the book. Nero persecuted the Christians. Nero was the seventh emperor of Rome. Nero was known amoung his conterporares as the "beast". So what makes more sense 666 means the devil :an imaginary mythological entity created from babylonian mythology passed down to the Jews OR Nero, the evil emperor of Rome that fits the description and time line? Sure you will pick the devil because Nero would debauch your beliefs. But again dogma always wins out over common sense in the religous arena.
"One is punished most for ones virtues" Fredrick Neitzche