Get the numbers
This idea of estimating Bigfoot's population is difficult. We assume by the Q Bigfoot exists. If so, then the extent of Bigfoot existing is the issue.
Here is my completely symbolic made-up the formula which defines the issue: B / T
That is, Bigfoot / Territory size or the vastness of the area.
Example: If you had 50 Dodo birds, and they were on a small island we would see them all the time. If you had 1,000 but they were in the vastness of some jungle, most natives might go their whole life and only ever see 1 on occasion.
We cannot assume all reports of Bigfoot are accurate. But, we cannot assume no reports of Bigfoot are accurate should Bigfoot exist. We are left to do a lot of guessing. If we can't have accurate numbers we are all guessing so we must make the best educated guess we can.
If Bigfoot is near extinct, then any guesses we might make of a viable population of Bigfoot would be way off. Why? Because a near extinct population would not be a viable number. Also, a population could not be assumed to be very high or sightings and filmings would occur all the time. To me this means the numbers must be very low.
Are sightings numbers going up or down? Are reports going up or down? Does that tell us anything?
Here is a final point to consider about these Bigfoot Numbers: There are more eyes in the form of cameras out there. In the days of the PGF there were few cameras esp due to expense. Over the decades, camera and later VCR Sony handicams became more popular and cheaper. Now Billions of Cell phones with cameras and video are out there. That would be Millions in the USA alone. This means nearly everyone out there hiking around looking for Bigfoot -and nearly anyone who is just hiking -have a camera with them. If Bigfoot numbers were high, we should have several PGF- level sightings.