Imagine your life being constantly under threat, some looming and semi-anonymous enemy who doesn’t care if you have a family or dreams for your future always just sort of waiting to kill you. You survive perhaps because of luck, and perhaps because of your ability to be highly intelligent, hyper-aware and to have quick reflexes. Most likely because of both. Perhaps you even saved others.
When you are ready to re-enter the “real” world of the United States, you find a gap between yourself and everyone around you.