Actually, I've not concluded with any certainty that the ETH is correct, only that alien craft exist and have been observed here on Earth. And I've only concluded that based on a combination of personal observation and the reports of many others who have reported similar objects.
No matter what you saw, you have no realistic basis to conclude any such thing.
One day when I was a young child, I was walking down the garden path at my grandfather's house and I saw something in the grass along the path that I could not identify. It was some sort of invertebrate animal, kind of like a slug or snail, only much larger. The strangest thing about it was that it was covered with ants and some kind of slimy froth, and was writhing around very fast, like nothing I've ever seen before or since. At the time it freaked me out so badly that I ran into the house in fear, and didn't tell anyone else about it. That sight gave me nightmares for weeks. To this very day, I have no idea what that poor, dying animal was, but I'm certainly not about to use an argument from ignorance to declare that it was something from out of this world. It was obviously just a thing which I had (and still have) no knowledge of. Being that it happened well over 30 years ago now, my memory is probably so faulty that I will probably never know for certain exactly what it was. Such is life. I'm not about to build an entire lifestyle around it and go arguing on Internet message boards that I saw something paranormal.
Had I never seen one myself I would still be of the opinion that some reports probably represent alien craft, but I wouldn't be entirely certain.
Seen "one" what? What did you see, exactly, that indicates it was something alien to Earth? A glowing light that silently danced around in regular patterns? How do you get from that experience to "OMG aliens!!!"?
You have no information on which to conclude it was an alien craft. No alien craft has ever been identified, caught or examined. All you have to go on is your own imagination, and the body of popular American folklore of the mid-late 20th Century.
Whether or not they are from another planet is something I have no firsthand experience with, so I am not certain about it. I'm a proponent of the ETH only because it seems to make more sense than other theories like transports from hell, time travellers, secret civilizations ... oh yes and witches.
You're a proponent of the ETH because that idea appeals to you, and you
want to believe. You appear to have built your entire self-identity around the belief, so of course you're reluctant to dismiss it as totally unfounded.
The thing you must realize though, is that your belief is every bit as faith-based as those of the Raëlians. You have no more evidence to back up your claim to have seen an extraterrestrial craft than the nutty Frenchman has to back up his frothy ravings about his own extraterrestrial origins among the Elohim. From any non-creduloid point of view, there's essentially no difference in credibility between your story and Raël's.
"Raël" just happens to have a ballsier and more compelling story than yours. You claim to have witnessed an alien space ship doing maneuvers from several kilometers away, but he claims to actually
be an alien from another planet. You went out and bought vanity plates for your car, but he actually had his name legally changed to his "alien" pseudonym. You're the sole proprietor of your own cheezy little online bookstore that masquerades as an international UFO club, but he's the head of an actual religion with membership in the tens of thousands, and recognized in many countries around the world. He has more pussy than he can shake his dick at, and well-founded plans to construct a UFO-themed amusement park in Las Vegas, and you're here wasting your time trying to defend your wimpy little story on a skeptics forum.
I guess my point is: as long as you're making stuff up, you might as well "go big" with it, and damn the nonbelievers. Either way, you're not being skeptical, scientific, rational or reasonable, and the only people you're going to convince are those who want to believe anyway. So why not just go for broke?