This is show throughout the movie by simply not giving Beowulf rewards other than being hailed a hero. That is to be expected whether or not he is materialistic since he did kill the terrorizing monster even if his rampages could have been stopped another way.
Overall if someone was to read the epic poem Beowulf and watch the 2004 film Beowulf and Grendel, they may be able to easily make out how much our cultural values have changed over time in regards to not only how we treat the idea of idealism but also how we see materialism as something to be ashamed of. In his roots, Beowulf is seen as a hero, a savior, a materialistic man, a man with the idea that he is greater than others, and a man who does not show mercy to beasts. This all changed when Hollywood got a hold of him and made him into the humble-hero we see in the movie