When I was in college I was in a class that was required to read a book, by my memory, called Republic of Grass.
The gist of the book, which was then a really hot item, is that the arms race between the US and the USSR, which was getting really ramped up at that time, was going to inevitably lead to a nuclear war destroying the United States. The solution, the author held, was to enter into a treaty with the USSR giving them everything they wanted. Complete surrender in the Cold War, basically. Better Red than Dead, more or less.
A few years later the Soviet Union collapsed.
In the 1920s and the 1930s the rise of Communist was held, in "Progressive" circles, to be inevitable and progressive. The outcome would be a world wide triumph of Marxism, which the arrival of the Communist in the Soviet Union made plain. About the only ones in radical circles, and even less than radical circles, who didn't hold that held the view that fascism held essentially the same future.
By 1950 it was plain that Communism was a hideous monster and we'd contest it. Lots of old Communist had dropped out of the movement forever, many when the Communist and the Nazis made common cause in 1939 and 1940.
All sorts of inevitable triumphs have been predicted, only to fade.
The only thing that's really inevitable is that nature wins in the end. You can act contrary to nature, physical or human, but you cannot disregard it. If you disregard it too much, nature ultimately gives you the dope slap.
This is something that is routinely ignored by politicians and movements. And of the right and the left.
We really can't do too much damage to the natural world before it gets even. This is science, and that has to be taken into account one way or another. To some extent you can take care of that through engineering. I.e., the river wants to flood here, I will build a levee. But you have to be careful. To nature, it still wants to flood there and it will work, for years, decades centuries and millennia, to do just that.
And so true with human movement. People can pretend there aren't men and women and that there isn't a reason for long lasting universal human institutions. But there is. Alter them too much, and human nature will decree you to be miserable in your alteration. Justice Kennedy can pretend whatever he wants, but declarations to the contrary produce misery, not bliss.
All of which is why nature wins.
Which is why philosophies contrary to nature loose.
Which is why political groups adopting falsehoods contrary to nature can sit and declare that something "is on the wrong side of history" only to find out that whatever they espoused was on the wrong side of nature.
It wasn't a pendulum swinging the other way. It was the hand of nature.