Of course not ALL boomers are whacked out lefties of some variety. And not all members of the WWII/ "greatest generation" are all that great. However, generalities can be gathered from how the vocal majority has behaved. Behind most america-bashing we see even today inevitably stands a baby-boomer.
I agree with your assessment of how it came about that so many of the boomers turned out the way they did. And I find that even those that came out of their tie-dyed clothes & complete craziness are STILL self-centered spoiled brats, even if they've entered societal "establishment". But no, not the EVERYONE in the generation.
When the VietNam war finally moved off of the back burner (remember it was a slow thing) a group of activists took it up. There already was a goodly number involved in the Civil Rights Movement, and this was a ready outlet for their try at being significent.
The Soviets picked up on the thread of this and abetted it.
The majority of this group weren't 'communists', or 'socialists' but rather idealists, who were manipulated.
Once it was put to rest (so to speak), and the Boomers came of age, they realized that there was no 'utopia', and took their place in the society and workplace. A small group remained 'loyal' to the thesis, and these became the nucleus of the radical left of the Democrat party.