What if the reason for secrecy is that the missing children/people are being traded to an off-earth civilization and as long as we trade humans to this alien race we won't be invaded/annihilated by the aliens? Or perhaps the flood of Noah and the previous civilizational resets were points in human history where the aliens reset the Earth because we decided to resist.

I'm not saying this is what is happening, just that it is a potentiality I have thought might be happening. And if it is the case that this is happening, I understand the secrecy.