Would you like to translate that?
I think he's trying to make a metaphor about not trusting anyone but yourself. Thus, water-proofing your boots that are supposed to be waterproof. Maybe.....
I'm guessing he doesn't trust the PGC's estimates?
There are those that don't believe the numbers, those that do and those that don't care. Of course it is all influenced by their own personal experiences, which is understandable.