First of all, there will be no "OMGZ ALIENS RUN FOR YOUR LIVES", because long before they make physical contact with us, they'll make transmissive contact first, to let us all know that they are human, not praying space mantises with squishy and crunchy exoskeletons. Of course if they're capable of getting here, they're not going to be grotesque looking things, they'd probably look caucasian, but far more attractive, and of course with much larger brains.. simply because the truth is objective, not as Star Trek would have you believe with butthead aliens running around pretending to be 'equal' under a communist government guised as a "federation".

My guess for the reason they're (real aliens) not here yet is because they're still too far away... and that's the only reason because all life wants to explore. Planet earth can only contain so much life, and the only reason it's holding up now is because we all still die. Immortality will only come with omniscience. And when we achieve that, we will know where those other beings are, and they will know us, and we will want to meet each other. So, eventually, like our ape-like ancestors left the trees in search of a better life, we will leave the earth in search for our brothers and sisters in outer space.

Forget all the hollywood <inappropriate language removed> brainwash about aliens, the real space aliens look just like us (if they are as or more intelligent than us). All hollywood has ever done was try to destroy nature, and desensitize people to their inner truths, and to create self-doubt in everyone.

What we long for, the reason we wonder, is the same reason we exist. There's something else out tehre, and we want to know what it is. The fact that we wonder and ponder about what is out there, proves that there is something out there, better than us.