The way I see it is if you are an atheist and believe earth has life as only possibility of chance then why wouldn't there be life elsewhere in the universe? if you are a believer in God and we are made in His image and when we create things (think artist, etc...) then why would God only create one planet in the entire vast universe with life? we generally don't create one great work of art, music, science, etc.... Why would God create only one planet with life? Simply because it is not discussed in the Bible is no reason, the Bible does not discuss dinosaurs either yet they clearly were a real animal.
I believe I have read that there it is a mathematically impossibility for there to be life on only one planet in the entire universe. What about the freedom of information act that has netted some interesting cases such as the tic tac videos of recent news casts. Also there are some pretty old art paintings that depict UFO's. If one keeps an open mind and researches there are many cultures that talk about visitors, watchers, etc....
There are astronauts that claim to have seen UFO's or UAP's if you prefer. It is becoming more mainstream to be able to admit to believing such things to exist and probably have been visiting earth for quite some time. It is usually the hyper religious who see such things as demonic rather than a curiosity that should be studied.
Why wouldn't another culture study us just as we study animals in the deep sea or on the land? Why would they bother to land on the White House lawn when they can clearly see we can't even get along with people who have different skin color much less say something much more fanciful in our minds? Our little minds preclude us from taking part in a larger community perhaps? Time will tell.