Emily's Cat
Rarely prone to hissy-fits
The out-of-nowhere aspect comes in when "drag" got transformed into "transgender" and was suddenly paired with "any male in a dress gets to shower with females if they feel like it" part of the activism.I don't think the pro-trans movement "came from nowhere in about five minutes."
In the early 90s, drag shows became fairly popular among young heterosexual women where I lived at the time. (Peoria, Illinois.) I think it was kind of an offshoot of gay culture becoming cool. (A few years earlier ('86), when I was in college, the "best" dance club was the local gay bar, which started having "straight night" every Wednesday or Thursday.)
Fast forward a few years to 1995, and To Wong Foo, Thanks for Everything! Julie Newmar came out and was a mainstream success. Ru Paul and Drag Race followed shortly after.
My point here is that trans or trans adjacent people became more visible in a positive light as acceptance of gay culture progressed. This likely encouraged people who had previously stayed mostly out of the spotlight to be more visible and vocal and, importantly, realize that they don't have to live in the shadows. (This is not a bad thing.)
So why the "sudden" appearance of more trans people?
Again, I think it is a delayed parallel to what I saw with the acceptance of homosexuality. In the late 80s, it seemed to me that there were a lot of high school girls who came out as lesbian. For most of them, I think it was a phase of social and/or sexual experimentation. It had become more acceptable to explore. (Oddly, it was (is?) not as acceptable for boys to experiment. Similarly, I suspect there are some young people who are experimenting. Not all, of course, but it's hard to tell one from the other.
So, no, I don't think there is some kind of conspiracy by pharmaceutical companies.
Drag becoming popular is entirely different - everyone understood that this was males dressing up as females for entertainment purposes (we'll just set aside my personal feelings about womanface shows). Nobody thought that these were males-who-think-they're-females-on-the-inside who were dressing up to perform as their 'true selves'.

