The answer "it's very funny" should not be ruled out.
It is a lifeform—a lifeform with a laser pointer teasing a cat.
Ultimately, an "explanation" that can explain any set of data is useless. I will grant, given the state of the world, "Because God is fucking with us," is an emotionally satisfying one. But ultimately it's just as unhelpful as "Because God wants it that way" from a scientific perspective.
There's a world full of natural phenomena which we perceive dimly. We try to create linguistic structures that explain it. A proposed change to that linguistic structure, like "Fairies are real," can only be more or less helpful in explaining the world we observe.
As George Box said, "All models are wrong; some models are useful." We should always be open to possibility. I am equally open to Bigfoot, UFOs, ESP, vampires, fairies, Santa, and Thor as explanations for phenomena. Which is to say that they are historically bad explanations that can never be disproven, but which have been demonstrably unhelpful in explaining the world.
If we find some Bigfoot like civilization living underground, but that's different to how we think of Bigfoot, we've "explained" Bigfoot and disproven "the wrong version" of Bigfoot.
If Thor lands on Earth and say, "I'm back," but says, "btw my name is "Bor". We've disproved "Thor". If we discover people with some disease which makes them live indoors, drink lymph fluid and live for hundreds of years, we've disproved "vampires" but explained the stories around that.
At the level of speculation we're operating at, these things can be argued both ways. It's not truth that brings you down on one side or another, it's your preference. You're blind to that.
It's the same deal with space aliens visiting Earth. The evidentiary basis for that is no stronger than that for aliens. You're correct that it's preference that leads some to favor aliens over angels, etc. But that's all it is.
It's an exact mirror of the practice you see of people who don't want to believe in aliens visiting Earth, inventing new ways to avoid the evidence, whether it's sensor data, witnesses whatever.
"The evidentiary basis for that (fairies and ghosts) is no stronger than that for aliens."
That's an objective sounding statement, but it's just your interpretation and preference. By what standard? If we had hundreds of thousands of people around the world saying they'd been raped / kidnapped by a gang of roaming miscreants dressed up as pirates, and these people had missing time, missing clothes, and then we had the EU maritime agency come out and say, "We've captured what seem to be swarms of pirate ships on radar". Would you still not believe them?
Possibility Prior probability
No aliens 0.55
Aliens at the perceptual limit 0.1
Completely invisible aliens 0.2
Obviously visible aliens 0.15
Now the math is simple. You cross out the impossible: obviously visible aliens. Then you need to get the remaining options to sum to 1 again. This is done by dividing by the total. Possibility Posterior probability
No aliens 0.55 / 0.85
Aliens at the perceptual limit 0.1 / 0.85
Completely invisible aliens 0.2 / 0.85
Obviously visible aliens 0
Now you may wonder where the prior probabilities come from. Well they are simply your best guesses based on reasoning and thinking, before having looked at the data. For instance they may be informed by your knowledge of physics and how easy it is to make things invisible. And they may be informed by extrapolating human psychology onto aliens (see the other response about a human playing with a cat using a laser pointer). You may consider the precedent of bacteria existing all around us for a very long time without detection.Which if I understand; would go like this on explaining UFOs:
Naive Approach:
P(ALIENS) = 50% p(~ALIENS) = 50%
Time elapses and I find some new evidence that looks like this:
P(Evidence | ALIENS) = 30% P(Evidence | ~ALIENS) = 90%
Which gives my hypothesis (Its Aliens) a posterior probability of 25% => (50% X 30%)/(50% X 30% + 50% X 90%).
I want it to be aliens so I say that they're conducting studies on us which juices P(Evidence | ALIENS && Studying Us) = 100%. But because I have no evidence to back that up, the odds are no better than 50/50; and I have to drop the prior of my new hypothesis (UFOs are Aliens who Study us) to 25% (50% X 50%). This nets out a new posterior probability of around 27%.
P(ALIENS AND They Study Us) = 25% p(~ALIENS) = 75%
P(Evidence | ALIENS & They Study Us) = 100% P(Evidence | ~ALIENS) = 90%
I'm new to Bayesian logic and am still shaky with it, so there could totally be glaring errors I'm overlooking, but as I understand it that's what I was trying to get across - Every new caveat you add to explain away a poor data fit shouldn't juice your odds.
It's an exercise in medievalist superstition dressed up in a cheap sci-fi veneer. Waste of time.
In some sense it's easily dismissed as "trivially lumping together all things we don't understand" and calling it "quantum". But on another level there does seem to be overlap: in types of experiences, places they happen, and other things I don't know about.