'We weren't being threatened by anyone when we went to war in Vietnam'

No but the Chinese subcontinent and the third world generally was being infiltrated by a very aggressive version of Marxism. I think it was a case of taking a stand somehwere. vietnam drew the short straw.

'And personally, if our own government becomes a fascist dictatorship, which it is well on its way toward becoming, I don't see how we are really any better off in the long run (as a country) than we would be if the fascists of Europe had won WWII.'

Take a look at Auschwitz, and repeat that. Ask virtually anybody, would they rather have lived in the 1950-70's in the Soviet Union or America. If you don't feel grateful and protective of what your political system has delivered thus far - well you should do.

The first imperative is to save your ass - take a look at those history plays. Anywhere can have a great constitution - most tyrannies have wonderful sounding ones. Not many places can keep the basic freedoms intact.