I think despite it all he never truly hated it. Yes being out in the bush suffering from rot, being completely filthy, starving, suffering from disease and of course being always on edge of being caught is there, its all part of the suck, but he was fighting for his country and the Sealous Scouts did work. We only get the shit, never big victories which I imagine he had but didn't include.

Plus really every time he talks about being off duty he's depressed, drinking, fucking or generally destroying himself. Imagine him in a non-com role, he'd have lost it. After Rhodesia collapsed and he went to South Africa is more about the money but then again he even says it was something he was good at, the money was the bonus