Spoilers about the ending.

Bateman hands the Spelling Bee Chair Director a letter and the director immediately tears it up. Bateman tells him, "well theres a part in there about you being my father" and he just looks at him kinda sad for a few seconds and walks away with the reporter who is consoling him. The director then woefully begins picking up all the pieces to read it. If the director hadnt reacted this way, dont you think Bateman intended to remain standing there in front of him so he could read it and understand?

I think Bateman in an odd way got to eat his cake and have it too. What I mean by this is that he got to tear through and blow up his absent fathers proud creation of the spelling bee and made such a flaunted mockery of it to really put his absent dad through the ringer over it, BUT he also won the Spelling Bee showing his absent father that he could be proud of his boy for winning the thing his father cared so much about.

Its a beautiful ending to this movie and explains so much of his behavior.