He doesn't care about them as long as he can do what he want. Have you watched/read Death Note completely?
I'm almost finished with the anime. Won't tell you where I'm at in the story for reasons of dropping spoilers for anyone who may not have read/watched it yet =/ Is the manga worth reading after I've watched the anime?
I didn't watch the anime but if the plot is the same what's the point of reading the manga? The manga is wordy and you already know what's going to happen. Unless you like to collect manga books and see the drawing style or something.
First, because the manga is the original version. The anime is an adaptation to another media. The manga is indeed wordy but it's easier to follow the character's reasoning, argumentations and deductions on text than listening to their endless talking ;P Besides, some scenes, even though almost the same, take a different approach in both versions. The most notable difference is the ending; in the anime it is very shortened and summarized compared to the manga, where everything is thoroughly explained. I recommend you to, after finishing the anime, read the ten or so last chapters of the manga. My favourite version: the ANIME LOL