I’ve been an amateur astronomer for fifty years. I have a somewhat realistic understanding of the distances involved. There is no conceivable reason to travel interstellar distances.
A technology developed enough to move between stars is developed enough not to need to. Whatever is seen in the sky has a natural or man-made explanation, IMHO.
I tend to agree. Physics as we understand it precludes a shotgun approach to interstellar exploration. It’s just too vast.
That is why I think this phenomenon is mostly terrestrial. It’s either based on lost science or physicists who went down another path.
Some of this stuff is not natural—at least in terms we understand.
People suggesting alien invaders or demons are either too gullible or too invested in their personal belief system to be objective.
But, yeah…space is very, very big.