"Oh my prophetic soul, my uncle killed my daddy!"

Another reason for Hamlet's anger and crazy behavior could be because he just learned his uncle might have killed his father. Besides the obvious, "Oh no, my uncle killed my dad, now I'm angry," he also would be mad at himself. He repeatedly said his uncle was half the man his father was, yet he pulled off a brilliant murder, right under every one's noses. He would feel disappointed in himself as well, for not stopping, or at least recognizing, what happened.