Others may set for grinding keys and constructing Hellfire Rings or create über avatars with über gear. Be that HC or SC.
The key word is "fun" and it is up to the player to find it in ANY game.
The last few days I also played with little cyclists to simulate the Tour de France or some cycling classics in a boardgame ...
I guess 99% of the people won't understand it, but the problem is that no one can define "fun" for each individual.
And Diablo 3 offers spades of fun for 3 million people per month apparently.
No need to try to counter this with useless posts.
D3 is there and liked by those who play it (be that from time to time or every week, day or monthly).