Amygdalatropolis

Alone in the stretching night. He'd wipe his eyes and climb the stairs back to his bedroom, and collapse amidst the crusted up sweats atop the mattress. He'd sleep, again. It didn't matter so much anymore whether the computer was turned off all the way, and he barely touched his dick at all.

As someone who spent quite a lot of time on 4chan in his younger years, I'm a bit impressed with how authentic the imageboard posts that fill a lot of these pages are. The hateful, edgy lingo is perfect. The homophobia, the misogyny, the nihilism, the racism, the aggression, the lack of empathy and stunted reactions to suffering... It's all there as this book really doesn't pull any punches. And it makes for a fascinating digital setting for this story about an American hikikomori, barely existing in this world while the glow of a computer screen and the gore videos on it fill his already deformed mind as he swings between his bed and desk all day and night.

This is a disgusting book that can be hard to get through at points, but it's also very clever in its presentation and really engaging in its character study.
The author manages to capture this sort of hypnagogic state where the reader is confronted with the different layers of the protagonist's existence simultaneously, similar to how one might keep tabs on different threads on a message board at the same time. The chaotic digital conversations, the depressing real life, and the protagonist's dreams and memories all fill the pages at the same time, structured with some different formatting for easier distinction.
Aside from the general atmosphere, it also makes for some effective clashing of subjects. Like, for example, when the reader follows the users on the fictional 4chan-equivalent gather to organize a really cruel harassment campaign against a random person while also reading the chatlog of a camgirl stream where an overzealous viewer tries to clumsily express empathy towards the camgirl who shows signs of self-harm.
There is a lot in here about the two-faced, twisted moralities and values of (predominantly) men who lost their sense of reality and compassion after escaping into the unfiltered depths of the internet for too long, wasting away while celebrating the suffering of others.

The main character is an interesting extreme for that and while he is just as despicable as the other anonymous imageboard users, it is compelling to read how his life had developed to end in this dark place, how his world-view formed because of that, and how he deals with inevitable change when he is confronted with it.
This is a quick read but not necessarily an easy one given many of the fringe and transgressive subject matters that take part throughout this in one way or another. But I think if you are in the right headspace to take these things on and are interested in an exploration of this sort of lost soul, then this is a surefire recommendation. This specific online subculture has probably rarely been displayed this authentically and raw in fiction.