So now it's "degrading" to use the word cultist for, well, cult like behavior? I don't think so. As for the numbers, I don't have hard data, and I cannot have data because what I would call "cultish" is hardly a set-in-stone definition, but to give a few examples:
Fanaticism != Cultism
Edit:
Until Bronco fans are grouped into the classification of a cult, I will stand by the above simple statement.