UFOs/aliens are like the ghost thread we had a while back: If you haven't seen them, chances are you're a skeptic. And I absolutely respect that. I've seen and experienced ghosts, and there are too many people in the Air Force and commercial pilots who have seen things that have defied the laws of physics.
Does that make them crazy? I don't think so. But I don't think we're as smart as we think we are, nor do we know everything. That's why all of this falls squarely in the realm of the unexplained. I just wish people would keep an open mind.