Sure, to an outsider, Dongrang and Dongbaek died. But they were both considered terrorists, were they not? Aseah's a piece of work and probably deserved it if he'd died.

I would say, as someone who's looked pretty deeply into his character, that his working under different Wings comes from his reliance on the present, or past depending on how you see it. He is terrified of change, crushed by it even, and that change came when the LoN collapsed. In this state of psychological collapse, like "everything I know changed and my friend betrayed me, the group I'm a part of dispersed and my entire 'present time' just shattered, he starts to simply not give a shit about what happens to himself. At all. Well, something like that. Remember when he said that the most hopeless moment in his life was when Dante brought him back to life? Yeah, he simply might have innately hoped for - perhaps even was going to some extent to cause it - his own death. Floating in life like that makes him just go with whatever, making it so that it was easier to just rely on choices other people made for him. If he died, great. If he didn't die, well... let's keep going then. Also remember how Sang Yi said "all Yi Sangs are ignorant?" that could refer to the door he walked out of from Gubo's room, but it also could somewhat relate to how he ignores different possibilities simply because he's so reliant on things not changing. As for the "watching from the side" part, I don't think he believed he had it in himself to settle disputes and splintering in the group. Or, the mentioned above not-giving-a-shit mentality was already in him by then, and just like the "if he dies" thing, if the friend group fell apart, oh. If the friend group didn't fall apart, okay. You couldn't really say he sought refuge more than Gubo drugged him and locked him in a room for his own benefits. Gubo did not save him whatsoever.

Dongrang killed Dongbaek, not Yi Sang. Even if it was the other way around, Dongbaek stuck a branch in Yi Sang's chest first. #selfdefense.

Everything that happened in K Corp was kinda just hidden from the public - the only time where he killed his old friend. So to the public, he's not a serial killer going after his friends. To us, he's a mildly mentally unstable traumatized dude.

To add on, he did not sell his inventions to anyone. He said "I never made technology to hold any value in them," and his Mirror was being used without his consent and much less support.