I had a neighbor who pretended to be military for the final 2 years of his life. He’d been claiming this a lot longer than that, but I only knew him the last 2 years before he succombed to his alcoholism.
His bookshelves were full of Vietnam books, had flags everywhere he could put them, etc. He could proclaim where he served, the unit, his rank, everything. We all believed he was a military guy up until he died.
His sister finally came to claim his belongings after he died, and when we asked her about his military service, she gave us the weirdest look.
Military Guy’s Sister: What are you talking about, he was never in the military. 


That made us look back and wonder why the hell he’d do that. My guess is that he was a scraggly 50’ish alcoholic guy. Claiming the military credentials would earn him points with everyone he would talk to.
Think about it, if he brings it up with a stranger who was in the military, he had an instant bond right off. If he told his story to a civilian, they would respect him more (and have no idea what he meant when he brought up E-2, E-3 ranks etc.) He told everyone he was living off a military pension, but it was really just SSDI.
If you’re approached by a scraggly old guy who’s just living off the system, you won’t respect them much. When the same scraggly old guy walks up and talks talking about killing gooks, sleeping in the jungle, foot-rot, etc… and knows enough of the in’s-and-out’s about the military to convince even military people that they served, he’s going to get more credit from the average joe. (And possibly some pity beer/groceries/handouts/etc.)
I still wonder what he was up to those last 2 years when he said he was going to the VA hospital 3-4 times/week