Is atheism a belief?

[Angrboda]

... for instance, whats the state for non-belief in Bigfoot?

It's called skepticism, and yes, sometimes that does shade into cynicism or pseudo-skepticism, but many skeptics do what Hume suggested a wise man do, and apportion their belief according to the strength of the evidence, without necessarily swinging the other direction on that account. Prominent skeptics like James Randi are quite explicit on that point.