If memory serves, we find out that Hive has been monitoring the MC to get him to join Hive's virtual world. We find out that Hive takes over each hosts body, performing their daily functions convincingly based on their observed behaviors. Then MC falls into the world and meets Buck. From here, we can deduce that Hive is also controlling Buck's body in the outside world. It's not a stretch to suspect that Hive is monitoring how they act in the virtual world, since it's Hive's world, and Hive's already monitoring the real world. Then Buck curses Hive, vows revenge, and shortly thereafter, gets killed by a monster that should not have spawned in that zone. It's Hive's game, seems reasonable to assume Hive wanted the Buck show to end. Seems pretty dark.