SHA - here is the thing. In my life, I have learned, even in my field of expertise, there are things and events that are unexplainable. So I will never discount the possibility of a "Bigfoot" existence. Or a UFO, for that matter. So, even though this creature has historically NEVER been found, killed or captured or the odds of a UFO visiting earth are mathematically infinitesimal, I cannot discount they COULD exist.
But I have, also, learned that humans are quick to label things and events that are unexplainable - most of the time incorrectly, I might add.
A classic example of this is your photo of a "nest". Your conclusion is that it belonged to a Bigfoot - with no evidence this is actually the case - because you believe such a creature exists. And because you believe this, you are ready to believe that sounds, obscure photos and hearsay from others is absolute proof that this creature exists.
You don't question the lack of a clear photo - even in today's technically advanced cameras - because this would throw doubt on your belief they exist.
Instead you choose to believe that "nests", footprints, hairs, sounds, obscure photos, hearsay and "experts" inability to confirm this "evidence" as something other than a Bigfoot, as irrefutable evidence they DO exist.
In other words, you are not a cynic like I am.