It's kinda hard to hide your lifestyle for over twenty years and nobody notice. Like I said, it's not easy; sexuality is something ingrained in us so turning that around is never easy. It takes years of support and work to turn. And you're right that you don't just quit practicing it but you must quit feeling it, desiring it, and thinking of it. When your whole life has revolved around one direction it's not easy going back another.
Well of course they haven't cured themselves, there's nothing TO cure. It's not genetic it an inclination. Inclinations can be turned, twisted, reversed, etc. The only known form of sexual genetic disorders are hermaphrodism and intersex disorders but those are rare. It's the same with pedophiles and criminals who try to claim the whole "genetic disorder" excuse as well. Yet nobody tries to make medications for ant-criminal behavior or sex offenders. It's cuz those people have to do it themselves as well.