Personally I want us to be alone just to disappoint everyone who jumps to the conclusion of aliens.
Personally I have no doubt that there are other civilizations at least as advanced as ours elsewhere in the universe, and probably elsewhere in our galaxy.
I equally have no doubt that we are unlikely ever to detect, much less meet, them. It's a VERY big galaxy, and our SETI efforts are both pathetically limited, and hopelessly misguided.
If we imagine an identical Earth 50 lightyears away, with people on it doing exactly the same things we are doing, then we can be reasonably certain that we would not be able to detect it. What few radio signals we have broadcast into space have mostly been of far too low a power to be detectable at such a distance even if we got lucky and happened to point our best receivers at that particular patch of sky. Only a tiny fraction of human radio emissions have been sufficiently powerful to be detectable (mostly Cold War era DEW radar pulses), and we only broadcast those for about four decades.
Our listening for radio signals to detect aliens, and concluding that they don't exist because we don't detect any is like a Hmong villager deciding that New York City doesn't exist, because no matter how hard he strains his ears, he can't hear any
whistle language coming from that direction. Not only would the signal strength be well below his ability to detect them, but New Yorkers typically don't use whistles to communicate.
Radio is almost dead after only a century or so since its birth, as optical fibre becomes a dominant communications medium; And radio signals that are broadcast into space are hugely inefficient, and our engineers take many steps to avoid such waste (unless they are trying to actively ping re-entering ICBM warheads). It would be difficult for us to detect Earth from even a couple of light years away. We are likely never going to detect any of the other civilizations with which we share the galaxy - even if they are relatively common.
As for having actual probes visit us, that's even less likely. The journey time for such a probe would be literally astronomical. As a result, the probability of such a probe arriving while we were technologically advanced enough to detect and recognize it are damn close to zero. Not zero. But damn close. Don't hold your breath.
