Long rant;;;;;
I'm in no way a professional, but as someone who had experienced several people like him, my thoughts were that Mincheol has something going on that wasn't diagnosed.
His problems started around mid-late high school, he started getting pushy, narcissistic, and impulsive. Most commonly in men ((((statistically)))), at that age and with those signs it's a big sign of mental illness. He doesn't quite live in reality.
The way he sees and handles money is another give at my idea, he believed it was easy money, but also realized it would likely come back to get him, so he made himself believe it was for someone else and therefore their responsibility. It's not uncommon for them to cling onto someone who's personality makes them feel obligated to take care of them ((((Coming from my personal observations, experiences, and light research, NOT a professional opinion). )))
You're not wrong that when it's his Mincheol's POV, things feel distorted.
Other people see this, when the individual does not. When they say things like that, it's mostly to make them feel "better" or out of pity - but from his POV, it's genuine and those people mean what they say. So they believe they're smart and attractive and will "act like it" (((Which is why you see those compliments when it's his POV, but not when it's a neutral POV... e.g. what we see from his colleagues.))).
He's bad at communicating because he doesn't actually understand his situation and the people around him, and expects them to instead because it's what they've always done around him. When people don't, or he doesn't hear what he expects to hear, he lashes out because he is impulsive.
His actions are by no means excusable, but with the patterns I'm seeing, whether the creator meant them or not, they are understandable. I'm certain he's now too prideful/ashamed to get help or even be able to admit something is wrong, but if he did this would be an entirely different story.
Despite their roles in the story, Taehee and Mincheol are my favorite characters. Unlike the others, they feel so complex and have so much depth.
Yes! I feel the same
People often misunderstand finding a character interesting because of their development with liking and supporting them as if we're in a parasocial dynamic with a fictional character
I feel like this is a complex story with characters that have bit more depth than the usual "dark romance manhwa" you find everywhere
I agree that he's AT LEAST delusional and at most an undiagnosed narcissist
I can also see the pattern and it's like watching a car crash in slow motion lol
Mincheol is such a unique character compared to what we see. Dark romance or even just the dark genre isn't just how violent you can get, how victimized a character can be, or how deluded one can be... it's about the what ifs. It's about the slow decline. It's being able to see a piece of yourself in every character without ignoring that the character is, indeed, a bad person. Stories that truly have that subtle gothic touch always catch me right on the hook (≧∀≦)

Can I be completely honest?
I thought it had taken him worse to become this piece of shit
I know that owning money, being beaten up and betrayed by someone he had a lot of trust is bad and could potentially change how a person views the world in a fundamental level
But I guess from the way I work, it doesn't make any sense why he would take out his frustrations on Haesu
The only reasons to do that are related to being toxic (refusing to accept he had a dumb moment, got screwed over and has to blame someone for the mistakes in life)
He couls have discussed with Haesu putting her name in the debt first.
He could've researched more about the "investment"
I don't know, I feel like every time we see things from Mincheol's pov, the way he sees himself is very distorted
He's always hearing he's smart and handsome
But is he really?
Realistically he hasn't shown to be too smart, he's actually somewhat hot headed and makes impulsive decisions and doesn't think long term. He's also not good at being communicating his emotions in tough moments
When she lost the baby, he lied for her sake, which she understood and pretended to believe the lie
But is that really a good way to deal with it?
In the end it only tore them apart, because it became a game of interpretation to Haesu that with time, turned into her justifying for helself his abusive behavior
Anyways
Mincheol managed to disappoint me even when the chapter was supposed to be this grand moment that justifies why he became a piece of garbage