One of the things I find fascinating about people who think UFO's are Alien Spacecraft of some kind is the similarity between the "evidence" for it and for the European Witchcraze.
For example:
1), In both cases much was made of the fact that many / most of the witnesses to it were sane, rational people not given to hallucinations, hysteria etc.
In case of the Witchcraze those who doubted the phenomena pointed out that much of the evidence came from people who were either crazed or tortured. But the Witchhunters said many / most of the people involved were perfectly sane and many were not even arrested but sought out the Witchhunters and calmly and rationally confessed to being Witches.
And these rational calm, uncoerced, people rationally and calmly talked about taking part in the Black Mass, the pact with Satan, flying through the air to the Witches Sabbat, sex with Satan, etc. How cried the Witchhunters could the skeptics reject such calm, rational evidence produced, by fine upstanding people like Lawyers, prosperous Merchants, Priests etc?
2) Firther the Witchhunters like modern UFO enthusiasts say if these accounts are the result of hysteria, fantasy etc., how come they are so similar to each other? How could accounts converge and seemlt support each other if it was all BS?
Thus the Witchhunters would refer to accounts in which two people who didn't know each other would describe seemly the same Witches Sabbat. How could this be if it was fantasy / nonsense?
3) Physical evidence Both UFO and the WitchHunters asserted that if properly interpreted there was physical evidence for their phenomena. In both cases broken branches, patches of ground that became "inexplicably" bare etc., were evidence of Witchcraft or UFOs as Alien craft.
4) And in both cases if you failed to accept the interpretation of the "evidence etc., like UFOs are spacecraft proponents, the Witchhunters asserted that showed you were closeminded and not open to possibilities that were clerarly indicated. ASo you has a skeptic needed to open your mind and not "dogmatically: reject the notion that Witches flew to the Sabbat where they celebrated a Black Mass, had sex with Satan, sacrificed babies bred for sacrifice, (All trace of being pregnant magically erased by Satan, and the Witches conjurted spells to summon even more demons bring on storms and plague etc. If you didn't accept that has a possibility that indicated you were claseminded and dogmatic and nort willing to look at the evidence.
5) Both UFO proponents of them being Alien spacecraft and the Witchhunters would concede that many of th cases were the result of hysteria, delusion, misperception etc., but there was always that unexplained residue that could not be explained in those ways so of course it must mean thast some of the UFOs are Alien Spacecraft and to the Witchhunters that Witches were absoloutely real, along with the pact with Satan etc.
Of course it turned out that the whole European Witchcraze was indeed a collective mass delusion. The whole Witches Sabbat fantasy was just that a fantasy. I suspect the UFO has Alien spacecraft is a similar fantasy.