Summarize Hamlet's monologue in lines 30-65 in ACT 4 Scene 4. Why is he upset?

Hamlet wraps up his conversation with the captain. He hangs back from the others marching to the ship and delivers a long soliloquy on the irony of this occasion – these men are off to risk their lives for a worthless piece of land, while he, who has every reason to risk his life in the cause of revenge, delays and fails to act. Hamlet resolves to recast his mind to bloody thoughts. Ironically, however, just after making this resolution he continues on toward England, leaving Denmark behind him.