In the end of chapter 2, why does Holden think saying "Good luck" is a terrible thing to say?

Holden says:

After I shut the door and started back to the living room, he yelled something at me, but I couldn't exactly hear him. I'm pretty sure he yelled "Good luck!" at me. I hope not. I hope to hell not. I'd never yell "Good luck!" at anybody. It sounds terrible, when you think about it.

It's a phony thing to say.  It's so empty, so overused that it means nothing.  It's like his mom sending his ice skates as a gift.  It's like the glad-handing head of the school greeting all the parents.  It's like having someone else write a composition about your room for you.  It's superficial.  There's no thought behind it.

It is also sarcastic.  Holden, though quite sarcastic himself, hates people who are insincere.  Remember, he yells something similarly sarcastic when he leaves Pency at the end of chapter 7: "Sleep tight, ya morons!"  So, "good luck" forshadows his departure from the school, which Holden would agree, is an omen of upcoming "bad luck" episodes.

As a funny side note, there's song by The Contingency Plan called "I am Holden Caufield" which borrows from Albert Kings's "Born Under a Bad Sign" lyrics:

A girl might build me up
But then I'd take a fall
Cause if it weren't for bad luck
I'd have no luck at all
Pretend I'm what I'm not
Packing heat to make me tough
Will I ever get a shot
To do what I love