Since it's /nightshift/ and schizoposting is usually welcome, I've been giving this serious thought.
Over 20 years of digging on this stuff and it seems like the greys are, in fact, harvesting some sort of biological material from human beings. People report collection of sperm and eggs, the implantation or extraction of hybrid fetuses, skin and blood samples, etc.
Moreover, I've come across a number of reports that these things, or at least the reptilians, feed off of negative emotions like psychic vampires. That would overlap with the basic premise of adrenochrome.
So I got to thinking…organ and tissue harvesting and sale. The sale of human flesh. Who would be the biggest buyers? Other humans? Probably not if one accepts that all of the above is true.
I won't claim to know what they are or what they intend, but I think that Planned Parenthood, the traffickers, the organ harvesters, and the corrupt biomedical industry are in some kind of covert alliance with the greys. I think they are the ultimate recipients of human organs and flesh in many transactions. I think they've provided biotech or the promise of it in exchange for human beings or parts of human beings and that they've been doing it for ages.