I’ve worked as a therapist, volunteer with marines at Pendleton, and addictions counselor with many veterans who were 22-30 and hanging on by a thread post service in Afghanistan and Iraq. The multiple forms of injury to body and mind existing in those conflicts heavily impacted young adults.
I currently work with mostly men in their 40s: it was usually early 00s when they were deployed. When they came back, they were veterans, and still are.