why do novel readers ruin everything

so I'm reading a manhwa and I'm sympathising for a character and comment saying they do not deserve what they're going through. why the ever loving shit do people think "let's not put a spoiler warning" and reply telling you the entire story about why the character is the antichrist???? CAN I NOT FIGURE THAT OUT BY MYSELF AND GET THE DAMN SUPRISE??? it ruins your anticipation and makes people damn near drop stories.

so my question is. Why the hell do you annoying shits do this?