There seems to be an inadequate understanding of what it means to prove something, in mathematics, in science, in jurisprudence, in life. Instead, we get this somehow Platonic notion of "Proof."
Sasquatch has been proven to me to exist, (generating a psychological state), and to many others (DWA for instance). The evidence and arguments used to prove it to us are varied. Most pass scientific muster, are logical, are statistical, are the most parsimonious, and would be publishable if the scientific process were not so dysfunctional.
The work that a number of folks have been involved with around ratio of bone lengths is hard science, and can be justified based on basic anthopological, anatomcal, and statistical grounds. It alone should prove to anyone with the basic scientific understanding, and a willingness to examine evidence in an open minded fashion, that Sasquatch is a real animal.
Not all will accept the extent proofs, and come up with far from believable alternative explanations for the evidence. As I like to day, "evidence free" assertions - some quite fanciful. Not all will even review the existing evidence carefully enough, with an open enough mind, to understand it.
Fanciful stuff:
a legion of costumed hoaxers
a legion of fake track makers, in the most absurd places for a hoaxer
multiple witnesses all sharing the same hallucination
collaboration amongst thousands of story tellers on obscure details to get consistency
stilts
impossible limb extensions
belief that such an animal could not exist
belief that such an animal could not stay hidden (surprise, they don't, all of the time)
belief that it is easy to find hidden animals in the woods
belief that the terrain could not support a large omnivore
belief that bones, and bodies of rare animals are easy to find
belief that it must have been a bear
belief that thermal images throwing nightime rock throwing are not compelling evidence
....
You can even be a fence sitter on the Skookum Cast and still be blessed with vast amounts of compelling evidence.
There is only one explanation which really honors the evidence, and makes sense - Sasquatch is a real animal.
Parsimony and logic!