They weren't.
The Vietnam War, and specifically the way Veterans were treated when they returned. Instead of being welcomed back as heroes, they were ignored because the war had been lost.
The Vietnam Veterans of America (VVA) has a motto: They'll never turn their back upon a veteran (as the VFW/American Legion/and the rest of the country did to them).
There are many websites by or for Vietnam Veterans. If you know what unit the vet served in, do a search for that unit. They might have an association to get veterans back in touch with each other. Click on the link below to see an example of a Vietnam Unit association website.
President Richard Nixon called back many Vietnam veterans under his policy of Vietnamization, which aimed to gradually withdraw American troops from Vietnam and increase the responsibilities of the South Vietnamese forces. This policy included the return of American soldiers to the United States.
Discrimination during hiring practices was widespread againt Vietnam Veterans; and Veteran's groups, would often discourage membership for Viet Vets. Which is one reason Viet Vets started their own Veterans Organization in 1978, the Vietnam Veterans of America (VVA); whose motto is, "we'll never turn our back on another veteran."
Many types of ways to acknowledge the sacrifice of Vietnan veterans came about after that conflict. Some states paid a cash award to veterans. Major businesses as well as federal and state government jobs gave hiring priority to Vietnam vets. The Department of Veterans Affairs (VA) offered generous educational benefits to allow vets to get college or trade education at little or no cost.
they were called baby killers because they would kill vietnamese children because they would try to kill them and themselves with grenades.
The Regiment began deployment to Vietnam on 16 August 1965 and the 2nd Battalion arrived in Country on 27 May 1966. The Regiment was back in California by May of 1971.
Generally, a Vietnam era veteran is considered anyone who served in the military between 1964-1975. There are, however, some nuances in the case of Vietnam War veterans, who served in country during the war. They can date back to the late 1950s and early 1960s, when the US had advisers in Vietnam; also, while there were only few in Vietnam at this time, some US servicemen who served in 1974-1975 would be considered Vietnam veterans (I.e. marines present at the Fall of Saigon and US Navy sailors who aided in evacuating Saigon).
Only some veterans go back. If they get called back or they choose to.
Vietnam
They welcomed him back.