suddenly all of the people fighting for it have two options: (1) stop and go home and be happy that you achieved your goal, or (2) continue to fight and just find something else to fight for/about/over.

No, they could have directed their resources towards places where homosexuality is illegal. But yes, all they gay rights activists just said "welp, we're done" and were taken over by TRAs because "you don't have to understand us, but our cause is exactly like yours because of this comparison, this analogy, and a healthy dose of shame if you don't support us, because don't you wish more people had supported gay rights when you were fighting for them? Nevermind that none of us participated in the fight for gay rights and actively work against them to this day.

not too long ago, homosexuality was considered a mental illness and it was not that long ago that it was removed from the DSM. So, even as recent as maybe 30 to 40 years ago, there were people that looked at gay people and said, "They have a mental illness and need to be cured of it." Then I look at some of the things that I've said about the T, specifically, "they have a mental illness and it needs to be treated as such and not just affirmed."

An unfortunate coincidence. Sexual orientation can be physically measured, while "gender identity" can not, because it has no basis in material reality, unlike homosexuality. This is proof that while homosexuality is not a mental illness, gender dysphoria is (which is an established fact anyway).