What is going on when Hamlet says this quote: "so, oft it chances......To his own scandal" (act 1, scene 4)

In this act and scene, Hamlet is waiting in the dark with Horatio and Marcellus for the ghost to appear. When Hamlet hears the gunfire, he explains to the others that the new king is having a party and celebrating too much. It's this kind of behavior that upsets Hamlet because it makes other countries look down upon the people of Denmark and make fun of them as a bunch of drunks. People don't stop and think about what Denmark has achieved, but they only think about their reputations as drinkers.This is just another example to Hamlet that something is rotten in Denmark.