I tend to agree with Greenwald on this point:

"Greenwald pegged the beginning of the trans rights movement to the end of the same-sex marriage fight, saying that the push for trans civil rights was a byproduct of winning that battle. Faced with either going home victorious but unemployed or pivoting to a new fight... equality activists chose to keep the spigot of cash flowing. "Instead, they immediately switched to the trans movement, which they barely had talked about before, because there was nothing else for them to do," Greenwald said"

When I first read this theory a few years ago, everything made sense about the current form of this ideology.