Mixed feelings about that. Having been a young sailor, (enlisted at 17) I can relate to the young Iranians who signed up to defend their country or simply to have a job at sea. My "war" was the Cuban Missile Crisis, and most of my shipmates and I were pretty apprehensive about the possibility of being torpedoed if TSHTF. And when we pulled into Guantanamo Bay to evacuate military dependents and civvy contractors we were aware that on the other side of that ring of hills was Cuban artillery capable of raining shells down upon us. They undoubtedly knew that they were targets, and I hope they had a "Come to Jesus" moment before they were wiped out.
I totally understand your concern. While I am sure for a few that is the case also a good many are vetted hard and they tend to be of the hardline ideological bent.