Physicist Fermi famously proposed the Fermi paradox: Given the Milky Way's ancient age and other factors, if there really is intelligent life out there, they would have visited Earth long ago; But the truth is that when we look up at the stars, we face what is known as the Great Silence. The universe is silent and tranquil.
The judgment that extraterrestrial intelligent life has produced many mysterious UFO events on Earth does not account for the Fermi paradox.