IMHO, First Blood was a good portrayal of what it may have been like for Vietnam vets coming home from a war they may have had no real purpose in risking their lives for, to a culture indoctrinated in thinking that the military vets were unassimilable psychos.
I remember reading First Blood and The Park Is Mine when the books came out. This was the beginning of the unhinged Vietnam vet genre. Hollywood claiming the fake moral high ground by making both stories into movies.