What kind of dumbasses think we pretend to be trans??

I just recently had some awful DM harassment from a transphobic idiot who told me that I was pretending to be trans. It was dealt with but I'm still left wondering. Why do some people believe that we would pretend to be trans? What do they think someone would gain by "pretending" to be trans. It just seems so stupid because I've dealt with so much oppression and people invalidating me my whole life, and yet they still think I'm pretending to be trans for some some reason...? Why? What the fuck does someone gain from pretending to be trans? This makes no fucking sense whatsoever.

Sorry for this rant, I really needed to get this off my chest.