I think they must generally be unhappy people who think that changing their genitalia will make them happier
If Joy is not Indwelling,
No one and Nothing here can give it to you
Surrender to God and His Gifts
Be Grateful for All Things, at All Times
Honor His Commandments
All things come together for good,
to them who love God and are
called according to His Purposes
Gratitude is not only the Greatest of all Virtues,
It is the Parent of All the Rest.
Cicero
They have real mental problems and need serious treatment, probably involving therapy and drugs. Unfortunately, they fixate on their genitals as the source of their unhappiness. They want to be someone else; one's gender is a fundamental aspect of one's identity--by mutilating their genitals, they think they can become a different person.
Sadly, they remain the same person, but mutilated, after "reassignment" surgery. None of their problems have been solved, and they have only added more problems.
The surgeons who mutilate these people for money are despicable. Yes, therapy is probably not as lucrative as doing the mutilation surgeries, and it is probably difficult--but that is what these people need, desperately.
We knew someone in the early 90s who announced that he was going to become a woman. Well, he went through the surgery and found that being a "woman" wasn't what he thought it would be. Committed suicide within a couple of years. Very sad.