Yeah, the X group should have attacked the O group at night to win the vote

Gi Hun's plan was too optimistic and had circumstances he could not predict.

The original plan already failed, since the tracker he had installed in one of his teeth was already removed, which means it's no longer guaranteed Hwang and the OPS will find the island, which means (at least if I was Gi Hun) that the best action course, would be to retreat and regroup with the gang.

Which leads me to the main question of this topic, the X Group needed to win the vote in order for them to leave and get out alive, something that can only happen if the X's attack first or retaliate the circles attack.

They had Young Il, Hyun Ju, Jung Bae and Gi Hun too, guys that can shoot well and fight too. The advantage was on their side and certainly more O's would get killed if they played their cards right.

When they won the vote, Gi Hun could reunite with Hwang in a safe spot and plan better, do more surveillance etc.,

Gi Hun advance with his plan based on raw emotion and moral, he didn't calculate the amount of red guards, nor the people that would join him.

The circle group has the old man, Yeong Sam and the druggie Nam Gyu, but they can be taken care of, either by Hyun Ju or Young Il.