A friend of mine, when he was a child, was abducted by aliens and brought aboard their vessel.
Here is the kicker.
I became a Christian years later and realized what really happened to him. It was a demonic attack. Some of these "alien" sightings are mis-identification. Some are military. Most are demonic.
Even that French guy who is an authority on UFO's doesn't believe they are nuts and bolts crafts but inter-dimensional.
Jacques Vallee -- His best guess is some kind of technology that transmits a hologram with mass. But he doesn't know and doesn't claim to know. He looks at the evidence and there is a hell of a lot of evidence that the skeptics dismiss with a joke. The skeptics haven't report the witness report and also the physical evidence. Saying that it's simply delusion or insanity is in itself delusional and insane. Look at the evidence that is out there.