Understanding Shakespeare's HAMLET - A friendly college prof discusses how Hamlet's weak plans and philosophical nature lead to delays in fulfilling his mission to kill his father's murderer
If this helps, my professor back in the day told us that much of the play was about indecision about the nature of his vision whether it is his father or not, whether it is telling the truth or not, and if true whether to act. He was like detective Hamlet. (My professor was a brilliant teacher, this a bare bones explanation compared to his lectures. So forgive me for the soundbite.)
Because hamlet is not a play about action. If it was we’d have had the pirate scenes. It is a play about contemplation, hence the soliloquys. Hamlet delays because he’s supposed to.