In the interest of clarity: A hypothesis that can't be tested, can't be proven - it does not mean that the hypothesis is necessarily "wrong" (or a fantasy). The observation applies to both "climate change" and "who might be an insider".

As an example, Einstein's theory of general relativity has been tested in several ways, and has not yet failed (a relative reminds me every time such experiment results are obtained). It is not yet "proven", but it survives as a valid hypothesis or theory.