In short, habitat loss. It appears from report densities that sasquatches need:
* Areas with extremely low human densities, likely because they recognize us as their greatest potential enemy
* Area with high rainfall, which is a necessary component for.........
* Densely forested area, which provides cover, and is almost universal with great apes
Rather than "need", sasquatches also appear to prefer:
* Mountainous terrain
As a low density, slowly reproducing omnivore, young maturing sasquatches would likely be required to relocate long distances to find suitable mates and territory for a new family. Thus, having good migration routes that are devoid of as many people as possible are needed. Such migrations could range up to 300 miles or more, which has been shown to be not uncommon for North American predators with similar behavioral patterns like grizzly bears and wolves. I think this would be difficult on a peninsula like Florida, and if such migrations occur, my bet is that they are now outward, not inward.