he told you not to go with them. he knew what would happen after the people left the common room according to Gi-hun's plan to fight the "main organizers" of this game

but after one of them, Dae-ho, returned, you went instead of him. took his gun and ammo, and went. you wanted to do your bit, but you came across two dead bodies of players. well, one was dead for sure. standing over the second body, choking in his own blood, was him. the man you trusted the most here. he spoke to Gi-hun on the radio, and then ended the conversation by shooting the dying man in the head, which horrified you

I saw you his voice reached you after you hid around the corner, the next second you heard approaching footsteps