Making protagonist that is unrelatable and unlikable has even higher risk and even lower reward.
If you need a protagonist that is relatable or likable to like the plot, this is a you problem, not a problem on the plot: some of the best fictions have protagonist that are unrelatable and unlikable and that's sometimes their entire point (or at least, you are making a mistake if you try to relate to them).
And in the case of corruption plot, making the protagonist unlikable is IMO the good choice. For proof, when you ask people for the best corruption author, they give you name like Shinra-kun (in the Fallen Star, the main corruptor is Lucifer, and by giving you his name, I have spoiled everything about its character traits and motivation), Maxcse (the only notable character trait of the corruptor in Dinaranger is an Hitler moustache) or Inoino (the corruptor in his story are either generically evil or monster): none of these corruptor have any relatable trait, and they are too shallow to be liked.
This works because the appeal of a corruption story lies in the corrupted, not the corruptor. Watching them falling, seeing their moral being twisted is why you read/watched/play those stories, whether they are porn story or not. I mean, the main character in Faust isn't the devil, it's Faust. And in the original Dracula, you don't know much about the titular character, but you will spend age on his corrupting influence on the main heroine, because, as with any well paced story, it focus most of its time on the character that change during it, not on the character that remains mostly static.