My model is that there's a sliding scale of how you'd identify your gender, and there's strong social pressure to conform it with your sex. As a result, only people who strongly want to identify their gender otherwise will. Another way to think of it is that the reason it's so incurable is that society automatically cures all the easy and medium cases.

There's instructions on LessWrong for how to become bisexual. If it's that easy for a heterosexual person to become bisexual, shouldn't it be easy for a homosexual person to become bisexual? It's the same issue here.