Holden's first impression is that of a person who hates people. It does not matter if he knows the people around him or not, all that he does is hate them for who they are. This personality of his is visible in every chapter of the book. Is this simply because he is a hypocrite? No.
There are many reasons as to why Holden acts this way. First, he is from a family where everyone except for him is intelligent; this fact puts a lot of pressure on him and therefore he starts acting in the way he does. As said in the book Alai was one of the smartest people in their family, D.B. is really smart as well, and Phoebe is also very smart. This leaves Holden feeling like he is disappointment to his parents and therefore his outlook on people in general becomes negative.
Second, Alai's death has a very big effect on Holden's emotional condition. This can be seen when he is lying down in the hotel and whispering to Alai, and also when he is crossing the road. Alai was one of the few people that Holden really liked and when he died Holden became so depressed that he broke windows with his fist and ended up with a permanent injury. It is possible that that event in his life changed his perspective a lot and he started looking at everything in a very negative way.
Third, Holden does not have anyone to talk to. He doesn't really have any good friends, he never talks to his parents about his problems. He likes keeping things to himself. This means that when he has had to solve all his problems by himself, he never turned to anyone for help. Eventually he started looking after himself and stopped caring for others. Thus, his negative personality became very solid in him.
