Thank you for that. Mostly, it was just the times we lived in back then. At least during my lifetime, it seems that the 1970's were about the worst period to be in the military. The protests against the Vietnam War may have started in the late 60's, but things really ramped up after the invasion of Cambodia in May 1970. People were angry about the war, angry about the draft, angry at the military, angry at the president, seemingly angry about everything. And that anger did not necessarily stop when the war ended in 1975.
I can recall people throwing trash at me and my Navy friends, pouring beer on us and cursing us out for the sin of simply being in uniform, well into 1980. (I'm sure it was much worse in the first half of the 1970s, but it was bad enough in the late 1970s) I wanted to ask them if they realized that the war was long over and that we had nothing to do with it, but it was pointless. So we tried to avoid wearing our uniforms as much as possible and grew our hair as long as we could get away with. In fact, I recall that, still into the early 80s, certain commands had restrictions on stopping anywhere between the base and your home if you were in uniform, so that they could avoid trouble.
Plus, the economy really sucked in the 70s. Inflation and unemployment were both high at the same time, and stock market returns were low. (remember the "misery index?"). By the time I joined the Navy in 1977, the belief was widespread that if you voluntarily joined the military (the draft had ended in 1973), you were either some kind of sociopath or a desperate loser with no future.
Add to that the fact that the military was itself "broken" by Vietnam. The equipment was dangerously worn out and/or in short supply, morale was at rock bottom, drug abuse was high and there was a profound sense of alienation from the civilian population. We certainly knew the country -- or at least the Baby Boomer cohort of which I was a part -- hated us. Sometimes, older veterans would offer us a quiet word of support, and that was quite meaningful, but day to day, things were grim.
I'm glad that you and the other younger active duty people and recent veterans are getting the recognition that you deserve and glad that the rift between the military and the civilian population seems to have been healed. I hope that division never occurs again. As for me, the Navy was good to me. It gave me the education and the discipline to make something of my life. (I really was one of those without other options). I got to do incredibly fun things and meet some great shipmates. And I got paid. So, I'd say no thanks are necessary for me. But I don't mind if people do thank me, and I try always to be gracious when that happens.
Good luck with your upcoming transition.