The Bigfoot-Dogman-UFO phenomenon could be seen as a projection of human fear and guilt onto the natural world. That may be a large part of what people are seeing, but I don’t think we can rule out the idea that something is actually there. It is not likely to be an undiscovered hominid, however. I expect it is best thought of as the same thing the ancient people experienced as “gods,” whatever that was.
The atheist cannot accept the concept of objective guilt, as far as I can tell. There can be no objective morality, and morality is only whatever the society chooses to enforce, which may change as fashions change. Yet many atheists believe in Bigfoot, in the sense of an undiscovered hominid, or primitive man-ape. This makes the god controllable, and makes him less than man.
This accounts for the popularity of Bigfoot as a subject of ridicule or nothing but an undiscovered species of ape. It is a way of ignoring one’s fear and guilt for not measuring up to objective standards of morality. It is a way of dismissing the gods, or God Himself, and His infinite demands on man for absolute perfection. It is an attempt at ignoring the issue, and dismissing the need for the righteousness of Christ to make one acceptable to Truth Itself, so that one can be in the presence of God in heaven.