Epistemic status: Big if true/I am clearly an idiot for even posting this.
Some apparently real journalists have been approached by (& approached) several intelligence officials, some tasked specifically with investigating UFOs, who claim that the DoD has had evidence of alien intervention for a while in the form of partial & mostly-whole fragments of alien aircraft. A followup article where the publication outlines how the editors verified this persons' and others' claims and affiliations is here, and a part 2 is expected tomorrow.
For some reason - very possibly because it's complete nonsense, or because they haven't had time to independently verify - the story has only been picked up by NYMag so far. The consensus among the people I've been reviewing this article with, is that it's either a complete hoax (i.e., the entire thing nearly top to bottom is some deliberate deception) or there's a non-negligible (>5%) chance aliens are here. I would love for someone who has a good understanding of the material to give an explanation (including possibly on priors, just thinking clearly about the content of the article) of why my friend group should discount this out of hand.
Thus far I have been unconvinced by most stories of why we should to-the-point-of-not-caring-about-UFO-sightings-expect Aliens have to be big and obvious and tile the universe with fun, as opposed to operating some sort of noninterventionist monitored lightcone.
My personal confidence of "no aliens" is so high it rounds to 100%. Placing a bet is basically just a loan with a weird "if aliens are real I don't get paid back" tacked on. The real question then is "at what rate am I willing to lend $X0,000 for 10 years to a stranger? If you can guarantee that I'll beat the stock market by 5% (conditional on no aliens) then I'm good to go, but the "guarantee" is very important. It needs to take into account things like bankruptcy on your end. I don't think our spread is wide enough to make that feasible. It'd take a lot of paperwork.
This is why we need real, formal, legal prediction markets, with derivatives. They would solve all of these problems.