Okay, go with the whole infinite universe, ever expanding, thus the Goldilocks theory we have here could easily be achieved any number of times elsewhere, fine. I can buy that. But by that same reasoning, assuming there is any infinite amount of possibility for life else where, you can't discard your own logic when it comes to 'visitors'. What would be the possibility of any other life form, out of the infinite choices, deciding to visit earth, not once, but literally thousands of times if even a fraction of the people claiming to see UFOs are to be believed. Not likely. It's literally 1 in an infinity that any organism would happen upon us, even one time in our Earth's existence let alone in the relatively small amount of time that humans have existed here. Again, its taking logic for one theory and throwing it out the window for the next because its inconveinent.
Soooo, I'm gonna go ahead and call shenanigans on UFO sightings.