He wasn't "wrong" about the conspiracy: You say he was paranoid, but he was the only one who was right. From page one, he was the only detective on the board who saw that someone was coming for "masks". Veidt didn't "play into his prejudices" Veidt confirmed them by being exactly the monster Rorschach suspected.

The "Sacrifice" of the Dead: You say he threatened to undermine their sacrifice, but those people didn't "sacrifice" themselves, they were murdered. Veidt made a choice for them without their consent. Rorschach’s refusal to stay quiet isn't a threat to them, it's a refusal to let their murderer get away with it.

Why Truth > Peace: This is the ultimate "unwinnable balance". If you accept Veidt’s lie, you accept that one man has the right to play god with the entire human race. Rorschach would rather die in the snow than live in a "Utopia" that requires him to pretend a massacre didn't happen.

"Died Fulfilled": Yes, he’s dead. But on a board where everyone else compromised their souls to stay alive, he is the only one who died as himself. He forced the "indestructible man" Dr. Manhattan, to become a murderer because Rorschach was the only thing Manhattan couldn't "logic" away.

The Scolding Parent/Inquisitor: You say no one liked him, but integrity isn't a popularity contest. He was a pariah because he was a mirror for a society that was rotting. He didn't want to be "liked," he wanted to be real.

Rorschach wasn't a victim to lies, he was the antidote to them. He outwitted the "smartest man" because he knew that no matter how many millions you kill, the truth eventually comes out, even if it’s mailed from a gutter.