Plenty of the guys in Perry's platoon have plans for what they want to do after the war. Brew wants to be a preacher; Monaco's going to get married. Heartbreakingly, we learn after Carroll's death that he was planning to open a bookstore with his wife. We don't know what Simpson's planning on, but he's definitely counting down the days. Brunner probably has people back home he wants to get back to bullying. Everyone's got plans.
Perry's a different story. He used to dream of being a philosopher or writer, but a not-so-helpful guidance counselor and the reality of his poverty didn't make that seem like a doable option. So he doesn't know what he wants to do next, which means he doesn't have anything to look forward to when he goes home.
Don't get us wrong—he definitely still wants to go home. He just doesn't know who he'll even be when he gets there.
Chew on This
The wife, future child, and bookstore that Lieutenant Carroll had to look forward to helped him to be a better, more compassionate leader.
The Vietnam War inspires Perry to want to do something more with his life.