I think it's less that he wants to see people dead and more that he wants his viewpoint confirmed.
I really liked Kazuya initially, even with his "evil" perspective on the world. Unfortunately it seems like Fukumoto got kind of lazy writing him. Fukumoto could have done a much better job giving him a gamble / game that better tests friendship to an extreme degree without needing to cheat, which would allow Kazuya to be twisted but still sort of relatable. He would be like the villain in Saw.