No doubt our profoundly unnatural educational system with its extreme age segregation has aggravated the degree of generational animus in the US.
Let's enumerate, I'm sure many of my readers can help fill in the gaps...
Greatest Generation <-> Boomers
Boomers say their parent's generation was distant, materialistic and never paid enough attention to them
Greatest Generation says the Boomers are selfish, ungrateful, and narcissistic. Generation X agrees with their grandparents' claim.
Boomers <-> Generation X
Boomers say that Generation X are cynical, lazy slackers. Generation X strongly resents the Boomers for failing to stay married (about half of Gen X'rs have experienced the divorce of their parents, with a majority of such divorces NOT being for one of the 3 A's)
Millennials are viewed as being lazy and entitled by the older generations. In turn, they greatly resent the bill of goods they've been sold as regards college degrees and employment (exceptionally high unemployment in this set right now)
The Greatest Generation by far has the best PR, escaping blame for many of the things that can rightfully be attributed to them. Millennials have by far the worst PR---few taking their grievances seriously even when they are actually legitimate. Boomers have by far the greatest political clout and control most of the engines of indoctrination. X'rs will hopefully step up to the plate as they gain political ascendancy and stop enforcing edicts that they don't really believe in but go along with out of fear of sanction or ostracism.