I think the hippie movement would have arisen anyway. It was based on pop music and boredom with the Boy Scouts, not particularly on Vietnam. Vietnam just made for more militant hippies.
One more comment before I sign off for a while, things getting very busy again - thanks for all the comments and such.
I didn't grow up then, so I don't know for sure - I know jus tthe normal course of events is for things to be like a pendulum in many societies, so that it's logical that it would swing *some* to the left, then maybe back to the right.
However, most of the popular music I associate with the hippie movement was written after the Vietnam War was in full swing. Summer of love...was that '67, going to San Francisco with flwoers in one's hair? Well, that's on the cusp, but the *major* stuff I see as like Woodstock, in '69.
I think a lot of hippies were a little bored, and wanted to try something different. However, I suspect that the most radical stuff happened because of some disatisfaction with the establishment over Vietnam and such. There was more a sense of hopelessness, from what I envision imagining myself being alive then. (And if i could see well enough to *be* eligible for a draf, and my muscles were better, and I could hear in stereo, etc.) I would think that many hippies felt a sense that they might as well party a lot now because they could be dead soon.
In other words, eithout that hopelessness, it's easier for many of the hippies to to be able to say, "Whoa, I've got a life in front of me, I can't be doing this to myself."
But, what do I know, I was always the geeky teen who talked about what he'd do in 20 years and actually *planned* for it, while not taking risks because I knew I could be throwing away my future. And, there aren't a lot like me, though there are some I know.