I recently wrote a section of Destroya that reminded me of how unlikeable the main character can be at times. I like her, but that's because I made her (though I don't like all the characters I create, especially not in this book). But I'm certain not everyone will like her, I imagine some people will probably hate her and they're allowed. I don't need everyone to like my work. But just how unlikeable can a character be before it ruins a story?
I know there are people out there who like morally grey characters, there's a whole sub-section of BookTok dedicated to the love of morally grey men, so I'm not worried about being in the grey area. There are lines even those who enjoy the morally grey won't have crossed. I don't think my MC has crossed any of those lines but I'd be interested in seeing what happens when someone does in modern literature.
When I think of unredeemable characters I immediately think of Humbert Humbert from Lolita by Vladimir Nabokov, iykyk. Lolita is a successful book, with a horrendous MC, so it must have other qualities that people enjoy. Personally, I have no great love for the novel, but I don't hate it either. Mind you it's been a long time since I read it, but I remember being disgusted but compelled to read on to see if this vile human of an MC got what he deserved. And maybe that's it? Maybe that's why I kept reading, maybe that's why lots of people kept reading, to see someone who was so repulsive (yet very real) punished. Is that the only way to have an unlikeable MC? For them to be punished in the end? I don't think so. So much of literature is subjective that there's always going to be someone out there who likes a character despite the awful things they've done (this may not always be a good thing though). I don't think a book like Lolita would be published today, because while there is a market for morally grey at the moment, Humbert is anything but grey.
So can you have a truly evil and unlikeable MC in today's market?