Self-Annihilating Fields

There is a curious phenomenon in our general subject of study, which I have anecdotally noted over the years.

Some sub-fields self-reinforce, people working in them are all very impressed with each other, they all think, or say, that what everyone else is doing is terribly clever and they're all doing very impressive research and we're all just so important and good.

Now, this is an over-generalization, but it is true, for example, that most cosmologists, or string theorists, will tell you how all the others in their field are really better than anyone else in other fields, and how even if they do things different, it is all good. They may concede that they think some are better than others, but they will tell you all of theirs are better than any others.

This is a good thing, it reinforces the field internally and in their interaction towards other sub-fields.
It even matters on little things, like faculty and postdoc search committees, or funding committees. These areas of study grow and attract more people who reinforce the attitude.

In contrast, there are other fields which self-annihilate. And, no, I will not be foolish enough to name any!

The pattern I see there, is that some senior people, often some of the founders, become negative.
Nothing and nobody is good enough, or as good as they were (or their great predecessors etc & so forth).
So they put down their colleagues, people who try alternative approaches are blasted for not following the one established technique or method, and in reviews they downgrade researchers in their own field, not on merit, but from spite and inflexibility.

Then they are surprised when the field shrinks, funding vanishes, no faculty are hired in the sub-field, and no one will hire their students for postdocs.
Of course they won't, there is no funding, because they blasted everyone else's proposals, so no one can hire even the people trained by the true Guardians of the Right Way To Do Things.
Ok, so nowadays there are all-field fellowships, but they can only pull a small number of people out of traps like this.
I don't think a single person can trigger declines like that, but a rivalry between two or three influential groups at a critical time, or over long enough a period, seems to be sufficient to trigger such declines. As with all destructive forces in academia it then takes a generation or more to recover, if ever.

It is childish. A simple failure of classic game theory, irrational people playing zero sum games, or worse still pathological negative sum games.
And, yet, intelligent people keep doing it, they just can't help themselves.

It pisses me off.
I hope I don't become like that.