Science is only concerned with the physical, as that is all that can be studied, measured and quantified in a physical world. If there was such a thing as "metaphysical science" we might be able to provide some kind of proof, other than memories. I'm sure you are well aware of this, which makes your comments over more condescending*.
You are also assuming that those who believe in rebirth have memories of previous lives. This is not true.
Belief in rebirth does not make one insane, as you suggest. If you truly believe this, then by extension, you also must believe that anyone who believes in God or some kind of higher power is also insane. That would make the vast majority of the entire world insane.
Now, I know others have started to avoid answering your goading* posts, but I'm sure, if you'd like to discuss the topic in a manner in accordance with right speech, I'm sure we can all have a harmonious discussion.
*condescending - Acting in a way that betrays a feeling of patronizing superiority.
*goading - Provoke or annoy (someone) so as to stimulate some action or reaction
*EDIT* By "metaphysical science" I am not referring to metaphysics