I interpreted it as MC having a super nihilistic view of things. A kind of "fucked up things happen to everyone, its life. Anyone can die at any time from any thing, even me" mindset. He's just so detached from everything in that intro, its not even about morals or benefit or anger or anything. Simply, the option is there, so he takes it. Nothing matters, so why not?
I wonder if Oceanlab thought that was a bit too dark. Because once the first day of school starts, MC is much more lighthearted, if "on-the-spectrum" emotionally stunted.
I'm kind of hoping it gets addressed again, because while fucked up, its a rare and interesting aspect of a protagonist. There's some good storytelling to be mined from it.