Well, I agree 100%. I might be biased though, because he is my favorite character (other than Sae-byeok). And he surely doesn't deserve all the hate.

But I don't think this opinion is so unpopular. Even some cast members mentioned that Sang-woo is also their favorite and the most realistic character too.

I think he is so hated because he caused the death of Ali (a fan-favorite character) and killed Kang Sae-byeok (another fan-favorite character). Also, another reason why he is hated is because viewers feel betrayed by him because they expected him to be one of the "good guys" and when he shows a ruthless nature, he gets judged more harshly than the organisers of the games.

Personally, I never hated him and I don't even see him as a villain because all of his actions were for survival in life and death games. If anything, the people who created the games are much more responsible for this even if they get a lot less hate.