Why do people so easily dismiss the possibility of aliens?

The 'evidence' is so sketchy. And people who say they've seen them always seen a bit... trying to find a respectful way of saying retarded.

From what I recall from one of those History channel documentaries, it was aliens who killed off the dinosaurs to extinction, then built the pyramids in Egypt and then left for their home planet in another galaxy. The aliens have not returned since

I find that people often use the words "UFO" and "aliens" interchangeably. Seeing something in the sky that you can't identify is enough to qualify as a UFO and I find it hard to believe that your coworkers (or anyone else) would have a problem with that.

A claim of alien visitation on the other hand has yet to be established. It's possible, but without evidence -- real evidence -- it's still an unknown.

Life elsewhere in the universe (if even in the past): almost a certainty.

Intelligent life elsewhere in the universe (if even in the past): I'd say probably. But super advanced intelligence? Who knows?

Intelligent life from outside our planet paying us a visit: No real evidence for that at present. So maybe, maybe not. The jury is out. I'll go with no for the time being.

I think it is mostly a religious thing. Somehow religion and life on other planets is incompatible. Although I'm not a follower of any faith and think they are very, very unlikely to be true (although I can't rule them out entirely), I actually think that if there is some supreme super being that created the universe and us, it would pretty much guarantee he made life on some other planets in the unlimited vastness of space so far away, we'll never be in contact. Without a supreme god, I still think there is about a 99.999999999999999999999% chance of life on other planets. But no, it is highly unlikely we have ever been visited by aliens.

First, it is a frightening thought for many. It implies that the universe is not in order as they thought. Further, like with other people of the Earth these beings most likely do not have our best interests at heart.

Second, as to science fiction people have claimed to have seen UFO's before the time of what we call science fiction. Ezekiel and the wheel in the Bible. Drawings of battles between space ships from the time of Renaissance Europe.

Third, we have to imagine a completely different technology than what is known to explain how beings could travel many years in a predicted life time. Just 150 years ago the thought of any space travel including going to the moon would have gotten a person locked away in an asylum for being mad. Today, we can and have gone to sites including Cape Canaveral to watch rockets and shuttles to be launched into space.

Extraterrestrial intelligence is invariably invoked to explain many unexplained or unexplainable occurrences, but in reality, it is the longest of long shots. The chances that aliens from other planets, or other stars, in the universe, co-exist with our own civilization are so low that they are almost immeasurable. It may be argued that a spacefaring civilization would have little interest in Earth, or as Carl Sagan suggested, that there is simply so much space between stars that, should two civilizations arise simultaneously in the universe, the chances they might actually meet before one disappears (civilizations come and go, you may have heard) is close to zero. Sagan's quote: 'There can be no 'Star Wars'.' This is not to say the chance is actually zero. But as our understanding of the universe slowly grows, the idea of a spacefaring, extraterrestrial race visiting the Earth, interacting with its citizens, and ultimately interceding in events here, may be easily dismissed. Sorry.

We know very little about our origins, about space and all that.
It would be naive to ignore that and .

We know nothing..

Nobody with a brain dismisses the possibility of alien life.

No, what the people with brains dissmiss is the UFOlogy myth of little gray humanoid aliens kidnapping and ass-raping humans! And we laugh heavily while doing so, because that one is SO clearly based on fears or desires that the UFOlogists refuse to admit or understand. Those bitches don't even understand their own thought processes, and still expect the rest of us to take then seriously ...