They can hate him for what he did to Chase, but they at least need to understand what he actually did, which sadly most don't. That is the problem.
You can hate any character you want, since you will find hateable aspects on every character. There is no exception.
But you need to consider that this is the comment section of "Desire me if you can", so it is totally legit to aks why they hate him. And most of the time the answers show that there is a massive problem concerning reading comprehension and/or a total weird view of the characters (including Chase).
So if the next one comes with "I hate him because of Chase" you automatically ask why...and start to get annoyed, when it is again one of those answers.
The question why do you even need to write it? You can hate him all you want, but why write here that you hate him because of Chase? Because the chances that someone asks why are high. And then you will have more here who not only read "Kiss me if you can" manhwa adaption, but also other works of the author.
U know ppl are allowed to dislike Grayson bruh. "He has mental issues" only explains his behaviour it doesn't excuse it. Especially since he's shown all Manhwa that he knows to differentiate between right and wrong very well. He might be nice deep down or whvr but ppl can still hate him for what he did to Chase. Stop getting mad at ppl just cuz they dislike a character that's the dumbest shii ever and they can still read this story cuz they like the dynamics and more importantly, Dane