I think Seungho simply just don't give w damn of how he's look at. To him nothing matters even Nakyum in the beginning was disposable to him but he started to catch feelings. So if he wants to bang Nakyum right there and then he's gonna bang regardless of what other thinks cause he don't care. And I don't really think that he anticipated any one to target a lowborn like Nakyum even going as far as spending money to hire someone
From the way he's been treating him since he fell I'll you think he'd think a little more protection wise. But I guess I'm the end it's ego and he'll learn the hard way
Curious why Seungho was so open about his r/s with Nakyum. Even if he's unaware he's developing feelings I'm sure it's at least clear to himself that he wants to protect Nakyum - doing all these things in public will obviously draw attention and contempt. I guess he was confident he could protect him, but it's foolish to take the risk.