You can't doubt reality. Once you get a true understanding about them and you keep yourself honest with yourself, an entire new understanding of our world begins to materialize. Bigfoot is merely a doorway into the true understanding of this world and humanities true existence. The truth is each of us already knows it but we are not aware that we already have the knowledge. Just as each of us have always instinctually been aware of the presence/existance of Bigfoot via our subconcious. Bigfoot has been a part of our existence for the past 12,000 to 20,000 years, over time we have interacted with them less and less.

Native Americans had regular interaction with them up until white contact.

Bigfoot has its own set of rules and laws, what these laws are I don't know, but it is pretty clear that they are not to interact with humans and to stay hidden. They tend to behave as if someone is always watching them.