Why are toxic tops such a hit?

Idk if this has been asked yet, but what's the reason behind so many manhwas having these good-for-nothing red flag tops? Is it because it's easier for the manhwa to get popular bc people will talk about it? Because the only manhwa that I can name which is really popular and has a 100% green flag top is Our Sunny Days(btw if you know any good ones feel free to recommend!!)