In this scenario of the breakaway, or hidden civilization, I would have to ask why they would even bother to show any aspect of their tech to anyone ever.
I think a lot of sightings are accidental. Some may be operational necessities that can't be avoided while others are planned for a specific audience, I don't know.
I don't think we can look at “them” as monolithic or contiguous. I see the possibility of two components. An older contingent that may be a “hidden civilization” that appears more indifferent to modern society than anything else. Then there is a the modern component that essentially apes the first exploiting the
idea of their technology if not the technologies themselves.
Of course the older hidden civilization part isn't really necessary. If you view UFOs and aliens and the modern equivalent of the gods, then it only follows that there would arise a “priesthood” who would exploit the belief in them to further their own ambitions.
It seems that some organization possessed invisible and silent aircraft as early as the 70s and used them in environmental monitoring and biological warfare tests in the United States. That is if you believe Valdez. Making it look like UFOs were responsible diverted more serious inquiry and consideration. A case where a “show” furthered their goals.
Are you saying that beyond that multi-generational wealth there is another group of humans, whose possession of unique technology, has kept their culture, location and operations entirely hidden from mass society?
I think it may be more like Dolan's notion of a virtual “breakaway society.” The majority of people participating in the infrastructure are isolated from command and control and essentially work for “them” but live without any direct contact or knowledge of the controlling faction. They essentially work for them and live alongside the rest of us.
Aside from those brief scenes in the sky, do you include any other aspects of the UFO phenomenon as part of this breakaway civilization i.e. abductions, contactee movements? The constant witnessing of tech just beyond our own is a common historical UFO theme and fits your theory. However, in those events, their is often a clear intention to be 'known' & to be seen - puzzling.
If you listened to people like Karla Turner then you begin to think that someone is running mind control and social engineering experiments, perhaps merely testing the apparatus rather than using it for its ultimate purpose as a weapon of war, on select members of the civilian population.
The assumption that they do things sometimes to be seen could be tests, mistakes, or even showboating. I think the idea is to pass as something else. To be able to come and go and be discounted as a hallucination, an alien, or not seen at all or to use the notion of UFOs and aliens as a means of psychological or sociological warfare.
The fact that these technologies are not overtly used in war or in political maneuvering suggests that the "command and control" see themselves as outside of the traditional political landscape.
Disclaimer: All of this is me just talking through my hat of course. I know nothing for sure. I don't have any documents, photographs, or tall tales told by men in trench coats to suggest any of what I have said is true. This is just another UFO buffs hair brained theory.
Can you cite any other evidence of their appearance on earth historically?
I don't know. Its easy enough to thumb through Vallee's
Wonders in the Skies and think that similar things have been happening in the skies and presumably on the ground, for a long time.