Reagan, Bush, Clinton, Bush, Obama, and a variety of other scientists and celebrities discuss the secrecy and the probability of contact with intelligent extraterrestrial life in the video below.
With so many stars with planets over so many billions of years, our discovery of aliens seems to be just a matter of time.
But assuming they exist, they may have already had millions of years of scientifically advanced technology to explore and look for others, including life here on Earth. Odds are, we were found long, long ago. So unless they have been meddling with life here for eons, they seem to have peaceful intentions.
I find the following idea/theory the most interesting: aliens have already colonized Earth long ago, and we humans are the colonizers not native to this planet – but for some reason our contact with the main interstellar human civilization has ended. Maybe a group of humans wanted a new start away from the mainstream. Maybe our ancestors were forcibly separated and placed here. And of course, the most likely scenario: maybe there is nothing to that idea at all.