Then what keeps people from just dying? I read fev had something to do with
From the fallout bible
Dying from what? Ghouls live longer than humans, we don't know why. Dying from starvation because they became feral? Who says they don't eat and drink? They lost their minds, their basic instincts have taken over, hence "feral."
The Fallout Bible isn't canon. From Harold in Fallout we learned that FEV and Radiation created him. We thought he was a ghoul, because he itentifies himself as a ghoul. In Fallout 2 he lives with ghouls in a city of ghouls of which he runs. So we though he was a ghoul and therefore his story about going into Mariposa in Fallout is what makes a ghoul.
But that is no longer the case. Harold is now a special FEV mutant and Fallout New Vegas backs up that radiation alone makes a ghoul.
Yes West Tek let out some FEV when it was nuked, but that was 200 years ago. People born centuries later are still becoming ghouls. FEV that was let out wouldn't still be around, and I doubt it was enough to cover the United States and it wasn't enough to mutate eveyone.
It is simply radiation that creates a ghoul.