It may seem obvious to you but i think it is wrong. I think the small critters are found because they are running on instinct, not intelligence. Bigfoot appears to be capable of the same level of planning you or I engage in yet we're pursuing them on their turf. If the tables were turned, if they were in our house rather than us in theirs, we'd find them pretty quickly, but that home field advantaged mixed with awareness and conscious planning are a hard nut to crack.
So far as "they don't exist" ... if that is the case, we need a rational and consistent explanation for the evidence they've left behind. Science hasn't been able to produce one, only excuses, only suggestions we not look at things that are inconveniently unexplainable if examined ... so don't look.
MIB