Despite his admittedly tragic situation, when Hamlet opines his fate to Rosencratz and Guildenstern (2.2.315-34), he is so verbiose that it is no surprise that Rosecratz rolls his eyes or smiles a bit. Does Hamlet overdo it? Or is it all a part of his grander scheme to manipulate his former friends?
R & G aren't truly Hamlet's friends and he knows this. He knows that their ambitious and desirous natures have led them to turn spy on their "friend" for a chance to gain favor with the new king. Of course Hamlet over does it. I think it's kind of his way of patronizing his supposed friends because they are overdoing it. They feign concern for Hamlet in order to get information for the king and queen and so Hamlet certainly plays up his own tragic situation to show them that two can play at their game and that he's got their number.
I think it is all part of Hamlet's grandiose scheme. Hamlet is amazingly intelligent. I love his character although he tends to speak in riddles so much that he leaves students befuddled. Hamlet knows his friends, and he knows they did not come of their own will. They were coerced into coming as they are "gentle" men and are looking for favor with the King and Queen...in lots of ways, but also with monetary payment. Hamlet knows these two have been summoned and therefore can't be trusted with too much information. He is playing with them and we get to watch. :)