As for the danger, population collapse is often precipitous - and by the time you notice it, is very hard to roll back.
And it's not just our species impacted by the changes.
Oh also since we’re on a technicality forum. Trans hormones don’t necessarily cause permanent sterilization. Plenty of trans people have children
> Of the adult trans population, between 25% and 49% of individuals are believed to be parents (Dierckx, Motmans, Mortelmans, & T’sjoen, 2016)
> Trans parents may form their families in a range of ways, including through biological parenthood, step-parenthood, adoption, fostering, and assisted reproduction, with an increasing number of options available to trans people wishing to become parents.
> Trans hormones don’t necessarily cause permanent sterilization. Plenty of trans people have children
I was just pointing out that the evidence provided with the 25% number doesn't really speak to fertility, but rather all the possible ways of having children.
And if it did, it would probably be from something like pollution/climate change, not a tiny minority of trans people.