Decent movie, stupid ending. (Spoilers)

PTSD can make people make stupid choices, but I think Jim was already violent and impulsive anyway. It wasn't PTSD, it was just Jim.

Obviously you've never dealt with anyone who has ptsd

I think the open scenes of battle showed that Bale was either kind of a psychopath to begin with or pushed firmly into that camp by what he had seen/done in the war. My guess is he was always out of control and hyper-aggressive if we're to believe as a white guy he grew up on the streets of East LA and managed to hang with those tough hombres.

I would kind of like to have known how he met his girl in Mexico. I mean she's living in a shack that's shacky by even third world shack standards, and kind of out in the sticks, too.

There's a part in the movie where Jim and Mike visit Toussant. This is before they all travel to Mexico towards the end. Toussant says while referring to Jim "The craziest head I know is going to be a fed."

So Jim was obviously crazy even before his military days. Probably when he was younger hanging out with Mike and Toussant. I'm thinking the military just exemplified Jim's craziness because Toussant also says something along the lines of "You used to be mellow."

I find it amusing that you say "the ending was totally unrealistic." Unrealistic to you perhaps but not everyone is of the same mindset as you. People make extremely stupid decisions every day. People do some things that makes other people scratch their heads and say "What in the hell were they thinking?" So I don't find the ending unrealistic at all, considering the entire movie, Jim is shown to be a hot head who acts on impulse.