I didn't have time to read the whole thread, so pardon me if I am repeating a thought. When I was a kid (to early teens) I soaked up books about UFO's and Bigfoot, and ghosts, etc. I'd go outside, stare at the sky, and hope to see a strange alien craft hover above.
As time has gone by though I have noticed that UFO sightings and Bigfoot sightings follow the same parameters. Blurry photos, plenty of hoaxes (though believers will swear the photos are real until proven fake), and absolutely no physical evidence that such craft exist. Sure---they can "claim" there is physical evidence (Area 51), but there is nothing concrete after 60+ years of scrutiny.
I am now convinced that Bigfoot does not exist, and I am 90% sure UFO's don't exist either. The only thing that has ever caught my attention, though it sounds silly also, is the 10% chance that the "craft" are actually time machines from the future, that elude radar detection and come and go quickly as they move from one dimension to another. This cannot be proved either, so even that 10% is extremely unlikely.
Think about the fact that one man--D.B. Cooper, "disappeared", in the midst of a huge forested area, yet they found some of his money there years later. Think about it, just one man, yet he leaves evidence that what he did was real! Yet years and years later there is still no physical evidence that either UFO's, or Bigfoot exist. You may say I am quite cynical--but I simply call it "facing the facts".