Will some mysterious hairs and photographs of a "face print" on a car window be enough to conclusively demonstrate Bigfoot exists? Put it another way... would a negative finding convince the fringe it doesn't?

Me, I stopped believing when I read that, for a species to continue existing, X number of individuals must be alive at any one time. The number varied, from as low as a few hundred to as high as a few thousand, but it was always a big enough number that I'm convinced something should've been found long ago.