Anything is possible, but that is no basis for an opinion, let alone a belief.  For the possible to become the probable requires that it fit in with other knowledge, that it have good supporting evidence, and that it be sensible.  A lot of that is judgment.  Way-out things, even with considerable evidence, are not acceptable without huge amounts of evidence and complete refutation of more likely explanations.

Basically whenever I'm presented with a situation where I can see no explanation except something extreme, I don't just assume the extreme.  Instead I assume I don't have enough knowledge and have to put it aside as unexplained.  Therefore argument that consists of nothing more than refuting alternatives is no way to proceed -- positive evidence is needed when the claim is outre.