Yes, I too believe in extraterrestrial life. There would not be just this one little planet with life, in this expanding, huuuuuuge Universe. There is life out there, no doubt.
But are 'they' humanoid? Are they like us? Are they capable of traveling many lightyears and have they or do they visit our planet? That's a whole other thing.
Many sightings are bogus. Only a few hold some merit. And even then, you would think there would be more solid evidence. So yeah I also believe that certain top secret military inventions or developments benefit from this cover story.
There are theories (a bookcase full of them) about aliens that have visited our planet in the past. Cave drawings, clay tablets, with very interesting things on them.
for instance, there's been 4000 year (give or take a while) old clay tablets discovered in the middle east, from the time of the Summerian people, that have a rudimentary schedule of our solar system drawn on them, including all the planets. So that means Pluto aswell. But WE only discoverd Pluto in the 1930's.
So how did the people back then know about the existance of this planet? Puzzling, if you ask me.
Fred