Avira:
Nobody self-identifies as “misnagdish,” and I mean nobody. Maybe a few baal teshuvos here and there who learned the term from Chabad then graduated from Chabad without learning proper yeshivish terminology. Even if someone genuinely opposed Chassidus, why would they make their entire identity defined around their stance on a movement they don’t hold of?
If you want to say other Chassidim use the term also, fine, but they’re also being derogatory. It’s not comparable to Yekke which is a clearly defined term and is used proudly as an identity. Misnaged has no clear definition and basically just refers to anyone Chassidim don’t like, much like when socialists use the word “bourgeois.” Are non-Chassidish sphardim misnagdim? Are yekkes misnagdim? Was the Chasam Sofer misnagdish even though one of his rebbeim was the Baal HaFlaah?