And how has that ever actually launched a career though?
It never has. Trooning out is useless in that respect.
To make them famous? No, I don't think that's worked, though it's certainly increased the focus on people like Caitlyn Jenner and Laverne Cox because they're considered pioneers for trans rights. There was troon/SJW outrage over Laverne Cox not being named Time's Person of the Year one year, because an online poll had her high in the rankings. Never mind that she wasn't at the top of the poll, the excuse they were using to say she should be on the cover. Or that the person they went for was, I believe, the newly elected leader of India, a country of over a billion people. It was Important, and so she only didn't get the cover because the world is full of Transphobic Shitlords, etc. etc. etc.
And I believe a number of covers with either her or Caitlyn Jenner have only been because they're trans. So while it didn't start their careers, it's definitely given them a very visible boost - there's no way Laverne Cox would have played Dr. Frank N. Furter in the recent Rocky Horror if she wasn't trans. I'd also say there's a number of trans actors who only have their roles because casting non-trans actors in trans roles gets you a load of REEEEEEing, as we saw with that proposed Scarlett Johansson movie. So actors on shows from Transparent to Grey's Anatomy, with their attempts to be woke, have only gotten their roles because of their gender identity.
Other than that, though, the main benefit for troons in getting a career has been people like the Google diversity hires like
@Ruin mentioned, or people like that Coraline troon who forced her way into a role as 'ethics officer' or whatever for the open source programming community. And I'd imagine there's a fair number of 'diversity officers' on university campuses that were only hired because of their gender identity - wasn't there one campus that was recently revealed to have over three hundred staff devoted to diversity needs/education?
In a way, it's clever, like the ideal marketing move of creating a new market so your product has a use, like with mouthwash. Still detrimental to society as a whole, though.