Excellent movie. I first watched it when it came out. Crispin Glover's performance is polarizing. Some feel he was overacting. But when I was young I knew people like him. Odd and over the top. Glover has said that his character was trying to get credit for being the guy to step up and help his friend who was in trouble. In some ways he it could be said that the character was "virtue signalling". There is a performative aspect to the character.
It's a dark movie. The idea that a group of friends have more empathy for the murderer, than the victim is scary. It's scarier that it's based on a true story.
Reading other reviews it feels like many of these people didn't like the movie because not many of the characters are likeable. It's an ugly story. But not every movie should leave you feeling good.