Well, to be fair there are and have been endangered species of animals with a total population down in the double digits or single digits.
Having said that, I agree we would have definitive proof by now. Scientists have been able to keep tabs on the rarest of large animals when they live in areas as remote as central Africa. The idea that such a large and unusual species could go barely detected in the tourist-attracting mountains of the western United States is hard for me to swallow.
But playing devil's advocate again, it could be said in all fairness that mainstream scientists have never taken Bigfoot (or any other cryptic) seriously, considering it a waste of time and resources. Since this is the case, nobody with the proper training and resources has even been trying to "keep tabs" on this, it's therefore been left up to mostly amateurs (and a few scientists) who lack the proper research funding and training to track down and observe such a rare and intelligent species as this creature would be.
And again, we're not talking about "tourist-attracting mountains" here, this creature obviously avoids these areas like the plague, we're talking about remote still-largely-unexplored areas. It's only occasionally therefore, when our logging and other activities push into new wilderness areas that
likely genuine contact has occurred.
The proper analogy here as rare species go, is with rumors of the Mountain Gorilla or the Giant Panda, both of which went unconfirmed for several generations before any hard evidence was obtained for scientists to study, prior to which mainstream scientists were just as dismissive of these creatures, as they are now about Sasquatch! Considering the modern hoopla over Bigfoot has only prevailed since about the mid sixties of the last century, we may have yet awhile before any hard evidence in the form of captive or killed specimens of these creatures (if they exist) comes our way?
What clouds the issue is all the hoaxes out there, if you see a fuzzy picture of a hairy creature that was supposedly taken in somebody's backyard (figuratively or literally) then chances are it's not real, these are a dime a dozen, and this makes it seem that Bigfoot are all over the place, when in fact they would be quite rare (again,
If they do indeed exist).
So I am inclined to be patient and reserve final judgment before dismissing the subject altogether.