The snippet tells us he feels gloomy and desperate.
But then it expands on that with a long, detailed passage of self-talk: he's friendless, nobody loves him, they'll be sorry when they find out they've driven him to a life of crime.
The close-up effect
Notice how this self-talk takes us directly inside Tom's thoughts.
We no longer have that over-the-shoulder sense of distance that we had in the previous page.
Instead we're inside Tom, experiencing his thoughts in real time the same way he does.