Loved this when I first saw it, I think it unravels almost everything about his character

The line where he says thay the gun made him feel noticed (for the first time in his life) ofc suggests that that he has had lifelong problems with self-worth

So I think he would have tried to fix this by adopting the 001 mentality to look at himself as above his fellow "trash" and inch closer to the VIP/001s level.

This level would be idolised, as it is the opposite of not being noticed. It's power, control. It's why he liked the gun.

and ofc this mentality - driven by his desire to be something - eats the remainder of the humanity spared by his feelings of worthless. This is what made killing his father a trivial matter, not that he was always psychopathic.

The result of all this is left side of his face. The smiling, spotless recruiter we know, but bathed in a red light that highlights his revealed ruthlessness.

The roulette game he plays is a wild west encounter with Gi-hun and his own moral standings. We know that he is fated to lose, and even this plot armour can be interpreted as the ever-present fallacy of his own life.

He had lost before he had even started the game; Gi hun reveals that through pointing out that he has always been their dog. The power perceived by his gun, by his role of recruiter, was a mirage. In following their orders, he was no different from the "trash". Even despite his nice suit.

Ddakji man realises this, and the reality of his life is captured on the right side. The blood is on his face makes him look unkempt, like a labourer. The lighting is whiter, more sincere. Like the red light, it reveals. The eye on this side looks bigger and vulnerable, betraying his weak half smile. We can now see though the cracks - and we see sadness.

He became cornered into confessing that he was their "dog" and so was no better than the "trash" he wanted no part of. He now had to look his reality in the eye. He didn't like it. He didn't want to accept it. And so he off-ed himself.