[I'm not a lawyer but spent way too much time with intellectual property lawyers]

Not true either for a digital book. However, since you are in possession of a digital copy of something that is definitely copyrightable, you have two options to defend yourself and not go to jail: either use the license terms that give you the digital rights to the book (and pay the $100), or not have a license, not have a defense, and let the judge decide what the penalty should be. Will it be more than $100?