Please thoroughly explain how World of Warcraft could be addicting?

The content of the game is almost endless. It's almost impossible to finish everything in the game. At first the game is boring and some quest or most at the beginning are. The game doesn't start till you reach your lvl cap..then well that's when the fun starts the challenges and well there's also the social part of it. Some people make friends on their also which makes it more fun. But I guess You can say every player has there own reason why they keep going.i.e raids/dungeons/achievements/social aspect/shear boredom with nothing else to do/But most of all I would say its the group aspect and social part in endgame content. plus once you've reached a certain point with one cl there are more and it starts all over again w/ different factions. Whatever haha I speak for my self here and if it wasn't for me getting in to this game or introduced to it..I guarantee I would be somewhere else getting my self into big trouble.