^Neapolitan, I doubt you are sceptic like I am because, and I don't mean to offend, but there are methods to being sceptical which I think you may not have heard of or at least don't apply much in your daily life. There are optimality criterions which let you choose one hypothesis over another even when you don't know which one is correct. Have you for example ever heard of occam's razor?
You are correct in that if I see evidence of the ancient astronauts hypothesis, I may change my stance. I probably will if it becomes the most
parsimonious explanation. Saying that these aliens may come from another dimension does not really make it much easier to accept. You then have to assume that the multiple worlds hypotheses are true, that beings are able to somehow cross over from one world to another and you still have the problem of explaining why we don't see these extradimensional creatures, their architecture, their technology and so on today. You know, why isn't our world more like Half-Life video game series?
I'm not saying these hypotheses can't be true. I don't know that. What I'm claiming is that the chances of them being true are much more slight and believing in them requires a range of explanations relating to them, and many of those could turn out to be wrong. Not that I study aliens, but let's say I could, then I would more likely do so when the support for their existence is so great that it should not be ignored. I wouldn't just do it out of the blue. That's when you say the ball is in the believers court - it's they who have to convince us, not us who have to "look harder".