"Unidentified flying object" literally qualifies a shadow that passes by your window that was PROBABLY a bird. In my neighborhood, it can also be an airplane. I can reasonably identify a bird shadow from and airplane shadow, but don't ask me to identify what variety of bird or plane from a shadow rushing over my window. Unidentified. Blurry photo of a balloon? Unidentified. So THAT kind of UFO, obviously. I believe.
Believing in intelligent life from space? Well, the universe is BIG. I won't even get into my theory on our use of the word universe, but there's approximately a metric SHITLOAD of stars out there, and we're finding more and more evidence of planets that have life potential. And we can't see all planets all that far, in the big picture. Across the near-infinite, the odds of other life are pretty darn good. I reasonably believe.
If you squint real hard, you can see 34638 bajillion possible hiding places for sexy aliens.
Believing that they come HERE? That's a trickier issue in my head. They're gonna be far off. I don't know what kind of engines these hypothetical aliens use, but.. it's still a long way off. And those hypothetical aliens might just now be mastering FIRE. Or have bombed their planet into a ball of radioactive glass billions of years ago. So odds are a little worse here. I'm on the critical side here.
I'm not saying Pacific Rim was ripping off the Beastie boys..
Believing that said visitors have been probing rednecks and inverting cows? Phew... I like to give folks the benefit of the doubt, and if your belief isn't doing anyone any harm, fill your boots, but I believe I'll pass on that tinfoil hat, TYVM.