Less than one in ten people who being transitioning step backward (“detransition”) at some point. Not all of them detransition completely.
About two out of five first marriages end through divorce rather than death. (This number is higher for second and third marriages.)
And yet… it is far more common for people to try to talk transgender people out of transitioning on the grounds that “you might regret it later!” than to talk people out of getting married, even a second or third time.
Keeping in mind: Transitioning doesn’t need to involve permanent changes. Many transgender people (like me) do not take any medical interventions at all. Some take hormones, which cause a mix of permanent and non-permanent changes. Some do undergo surgery.
Also keeping in mind: Most people who detransition don’t do so because they realize they’re not transgender. Sometimes it’s for medical reasons; hormone replacement therapy for trans women can cause an increased risk of heart problems, for instance. Sometimes it’s for social and mental health reasons: There is so. Much. Stigma to being transgender that many trans people decide it’s easier to just go back to pretending. (This, not “I decided I wasn’t trans, is the most common reason.)
The actual percentage of people who start their transition and then realize they’re not transgender is much smaller, probably less than 1%.