I think they are smart enough to realize that by showing up they had better have their shields up for we are stupid enough to shoot at them. Those who would do the shooting would be surprised by the return fire.

That would be my inclination as well, but I think that in this hypothetical, we have to assume that your therapist - indeed, every therapist - sees the UFO also. Now, you could assume that we are all experiencing a mass delusion, which is plausible, but the question remains: from whom would you seek medical/psychological help?

Indeed, if all sane people see a thing, one must either assume oneself sane, or join the crazies in denying it, despite the evidence (ahem Flat Earthers, I'm looking at you.)

@Fernapple Delusional. Really? Perhaps you can offer some explanation as to what it is that military pilots, airline pilots, satellite photos, and huge numbers of people and devices photograph that cannot be explained? I'll take any reasonable terrestrial explanation, honestly. Certainly the authorities have long given up blaming these things on Jupiter, ball lightning, aurora, and reflections of the moon. The age of the ubiquitous mobile phone with HD cameras and videos have ended that. Even military people, hardly members of the lunatic club, acknowledge these things are inexplicable. But you say it's all delusional and people need therapy. I myself am not making any black and white conclusions, but nor am I prepared to dismiss this as lunacy. Moreover, we as a species have gone from horse and buggy to spacecraft entering the outer solar system and spacecraft on planets in 150 years. That's a nothing period, in species timelines. Gosh, I wonder what might be achieved in centuries and millenia, elsewhere? @AmyTheBruce

@David1955 I would never have said that UFOs don't exist, in fact such is the human capacity to see things, which are not there, or mistake things for other things that it would be surprising if there were not any. But we are not talking about UFO sightings, but actual contact on the ground. While in the opposite direction if there really were E.T.s out there close by, then you would expect that the first plausable evidence would come not from earth but from astronomy, radio finger prints and the like yet we see nothing, so the opposite goes that you must explain the Fermi paradox.

Travel at the speed of light is an impossibility. Unless there is intelligent life in our solar system, ETs getting here is also damn near impossible, as is the existence of God. I will not keep an open mind about the supernatural, life after death, deities or little green men.

@barjoe such arrogance, not to acknowledge what you don't know, what might be possible in science, what we do not fully yet know. You, a guy in the 21st Century, boldly claim that travel in the universe is impossible because the limit of your current scientific knowledge tells you that. Well, I'm not so dogmatic or arrogant. Yes, i believe in evidence, but we are not talking about an imagined heaven, but a real universe, and I respect what I don't know. Tell you what though, this subject is unfolding at the moment, as a number of articles have acknowledged recently, and should something credible break, I'm going to remember and quote your comment back to you. I am blessed, or that cursed, with a very good memory.

@David1955 No need to get upset. I've come to the conclusion that infinitesimal possibilities can be called impossible. I like science fiction. It's fiction though. I'm not screaming from the mountaintop. You believe what makes you happy.