They are afraid that since this is the very best video gaming has ever been, they are scared that nothing will be able to compare to it in the future. And that scares them thinking that they will never get the same enjoyment they just got, and so they respond angrily.
They are angry because this game means all their other games are now worthless. It means all their time and effort put into other games is meaningless, because the only thing that matters is Crysis 2. This angers them.
Because you are reading this, and on Crysis 2 forums, only proves that the only relevant game is Crysis 2, because it is the very best. This is all the truth and you are afraid to confront it, but it is real.