Not long after the second world war the military was playing about with 'quad-copters', that is, with drones of the sort you can now buy in hobby shops. They were not as sophisticated as todays UAVs but, because of the way they could hover, dart about, climb and descend rapidly bla bla bla they were described as 'alien technology'. Nobody had seen things flying about like this before. As more and more 'UFOs' were reported, it was in the interest of the military to let folks think they were from outer space - keeps the heat off the secret stuff occurring here on Earth. Has anybody ever wondered why today with our high resolution cameras we still only ever see blurry crap images of 'UFOs'?
Dick Smith's offer of $100,000 to anybody who can prove UFO's from outer space exists stills stands as far as I know. Some folks will believe so intensely in something (flat earth, UFOs, visiting aliens etc.) they will totally ignore any scientific explanations to the contrary. It's human nature I suppose.