Jude was the only one who "got" what Jesus was about - in order to free Jesus' soul from the "prison of the flesh", he had to "betray" him,
But why does jesus say this
"But woe to that man who betrays the Son of Man! It would be better for him if he had not been born."
This doesnt seem fair in any case :S
Judas really "getting" the point, would however be more believable, since they also knew that according to the prophecy, one of them had to betray jesus, and this was supposed to be. Then, it would make sense of one(or all) of them to think, that they are the ones who will have to do it.(as a favor, since they dont know, if others will, and without them, the prophecy may be not fulfilled)