This is acknowledged in the book, which admits that not all Lemurians are sadistic psychopaths, and quite a few of them are decent people. On the other hand, they are delusional, and believing absurdities leads to committing atrocities. It does not help that the Lemurian worldviews are profoundly anti-human, viewing mortals as resources, problems, or enemies, or that Lemuria as a whole is schizophrenic. One day, a Lemurian might sell you 20kg of plutonium, the next, his boss sends 6 men with spiders for hands to kill everyone you love.
Chejop Kejak, leader of the Sidereal Bronze Faction in Exalted. He masterminded the Usurpation, an event which wiped out the Solar Exalted and ended the Age of Dreams, because the alternative was to take a very risky path to redeem the Solars that would, in all probability, have led to the destruction of Creation. Unfortunately, the side effects of the destruction led to the creation of the Deathlords and the Great Contagion, and Creation only survived the backlash by sheer dumb luck and a foulup on a Deathlord's part; the fallout from that event and Kejak's emergency responses led to the creation of the modern Realm, a corrupt dynasty of Dragon-Blooded nobility far degraded from even the Shogunate. To make things worse, Kejak has developed into a Knight Templar, constitutionally incapable of re-evaluating his standing agenda in light of the current situation. To be fair, that's the effect that the Great Curse has on all Sidereals, IIRC: to be completely unable to see any flaws in their primary motivation, whatever that may be.
As one friend put it, the greatest manifestation of the Great Curse was not any Solar jerkassitude (even Desus, he might just be evil, after all), but the life of Chejop Kejak.
Also, Abyssals 2e reveals that the creation of the Deathlords is the fault of the Gold Faction, not the Bronze: if they hadn't gone into the underworld and stirred up the memories of powerful Solar ghosts while trying to dig up secret information on the Bronze faction, the Neverborn might never have scented opportunity. So Kejak's sole contribution to the creation of the Deathlords was to inspire the people who didn't like him to do something epically stupid in the process of trying to shank him.
That and, y'know, getting the Deathlords killed in the first place.
To rephrase Kejak's actions' motivation and their consequences, Kejak acted as he did in order to save the world. As a result of his actions, the world has died by inches, growing less glorious and closer to destruction with each cataclysm (until the present, when it's getting glorious again but seems more doomed than ever). And he can't see, much less admit, that he's wrong. Perhaps the inevitable result of playing it safe in a setting that runs on the Rule Of Cool taken Serial Escalation.
Strahd von Zarovich, seminal villain of the RavenloftDungeons & Dragons setting, flirts with the Anti-Villain trope from time to time, particularly where his past history as a war-hero and his steadfast defense of Barovia from outsiders is concerned. The rest of his past history, together with the fact that he's a vampire defending his larder, keeps him from slipping into it entirely.
The change was that it stopped being "let's become evil sorcerors", instead, he made a pact with Tzeentch to save his legion from extermination and it blew up in his face, killed everyone on his homeworld, and started Ahrimahn on the path that lead to the creation of The Rubrick.
Alpharius could also be this. He had a secret meeting with the Cabal, who told him that the only way to destroy chaos permanently was to make sure that Horus would win.
When it comes to Warhammer 40,000, Cypher tohas is the absolute personification of this trope. His goal is possibly the most noble and true goal imaginable: to reforge the sword he stole from the Dark Angels in his youth, and present it to the Emperor to attone for his considerable sins, which he knows will likely lead to his death. But because of the things he's done, it's impossible for him to go about it in any way resembling "good". Everyone in the galaxy sees him as a villain, he's infamous. But he's desperately trying not to be.
