They get be part of a group supported by progressives, rather than having to handle their problems alone. They can potentially get bisexuals, especially the one like "I like dick but hate men" type or other transbians for sex and relationships. And can attack women who don't want them, by making them pass as transphobic bigots. There is some advances if you think about it. And if a male id desperate enough, he can even think to castrate themselves if the alternative is being alone against his will.