The logic is quite simple: the KJV mostly follows the Bishop's Bible. If the Bishop's was not inspired, then the parts of the KJV that follow it are not inspired. There are places where the KJV follows Beza. If Beza was not inspired, then neither is the KJV.
There is absolutely no reason to believe that the KJV was inspired and that other translations aren't. It's pure groundless speculation. You as the KJV-only proponent are making the claim that it is inspired. By claiming that "nobody gives reason or evidence for saying" that it isn't inspired, you are making a burden of proof reversal (a logical fallacy). You have given your side; it has been rejected as illogical, groundless, and circular. We have no need to give further evidence against it.