"I think he's a spy from the people who put us here." […] "We can't trust this shank," he continued. […] "There's too many weird things going on, and it all started when this shuck-face Greenie showed up. And he just happens to be the first person to survive a night out in the Maze. Something ain't right," (24.50-54)
When you know you're being played with, it's hard to trust anybody. It's also pretty easy to lay the blame on the nearest scapegoat. That goat really should avoid these situations.
"No one ever understood what I saw, what the Changing did to me! Don't go back to the real world, Thomas! You don't… want…to remember!" (39.19)
Ignorance is bliss, Gally.
"You shut your shuck-face, Thomas. You shut up! I know who you are, but I don't care anymore. I can only do what's right." […] Gally gave Thomas a long, haunted look, his eyes full of terror; then he turned and dove into the writhing body of the Griever. (39.14, 20)
So, killing yourself is "doing what's right" here? Is self-sacrifice always the right thing to do? The benefit is that he takes one for the team by filling the "one kid abducted and killed per night" quota.