Not sure if there is an accepted definition of "fan" out there. I watched every Ram game to the end even if I'm at the stadium and their hopelessly losing. I just have so many memories of the uniform and how that relates to me growing up I can't bear not watching them. But I know die heart Ram fans who can't bear watching what they consider a bad team. Much like a wife who knows her husband is fooling around. She still loves him but won't sit still and accept his behaviors.
No one has the monopoly on what a "fan" really means.