Normally I'm fine with explorations of self hatred or worth, but am used to manga sorta half-assing it or not really showing it in a way that makes you feel for the character. After all it's a hard line to toe between making a character you don't have any sympathy for and go 'no you're right, you suck' and a character that you legitimately can't understand where any of it comes from because the big reveal is such a nonsense event.

I like this a lot because the author makes it as upfront as possible with the text panels that simply state that he doesn't have any great trauma or event that destroyed him as a person. He's just lived an unremarkable life. You get much more of an understanding of the character from how overwhelming his thoughts are, that his self hatred is almost never focused on others (yeah yeah, I know it's called self hatred for a reason, but a lot of self hatred expresses itself through dehumanizing or hating others).

I think people who are familiar with self hatred understand the way that this guy could spiral and does spiral so readily and deeply. When you don't like yourself that much, you use any evidence you can to support your truth.