We are finding that most young people today have less ability to handle stress. Most were not into competitive sports, most have never been around old people nor have seen someone die (ie a grandparent).
People used to have coping mechanisms, a large family (support group) and often a sense of faith. Now most have nothing.
We are also finding that many young people can not deal with the physical stress of Basic Training. Too many kids have such low bone density that they have massive stress fractures just from marching and have to be discharged (30% for the Navy, 18% for the Army).
Makes me wonder what people would do if something big every happened to society. I doubt many would survive. It is very clear that few could be the frontier pioneers that our ancestors were.