Any ideas on the background of the killer?

I know it's a movie, but how was the killer able to do everything he did? Not only did he seem to have a good amount of combat training, but he also must have been somewhat wealthy, judging by all of his gear and his ability to leave everything and move away with his two victims. It would be more believable if he was an older guy who was already wealthy, but for a young guy, how did he manage all of that? He reminds me of The Hitcher...nothing is revealed about him, so it leaves you wondering where he came from and how he survives.