God bless young transsexuals nowadays! More and more grow up knowing who and what they are. If their parents are enlightened, they change sex early enough in life so that they never have to go through the wrong puberty and the resulting irrevocable physical changes. If they have to wait until they leave home, they will then have gone through the wrong puberty, but at least they probably won't have developed a persona to go along with the physical body they were saddled with, a body that is still fairly maleable.
Changing sex later in life is more difficult physically than doing so when younger. There are all kinds of sex-related characteristics that become more pronounced with age. But perhaps more important than the physical difficulty is the psychological difficulty, at least for some.
The longer a person lives as the wrong sex, the more likely they will develop a persona that matches their physical body. This is especially true if the person has been very susceptible to gaslighting, believing what others and their own bodies are telling them instead of trusting their own thoughts and feelings. As time goes on, people establish lives. They get jobs, become involved in relationships, get married, and even have children. They become more and more invested in the status quo.
The more investment there is in the wrong-sex life, the more distressing it will be when the effects of gaslighting wear off and full realization hits hard. Those who change sex early in life have most of their life ahead of them and very little behind. Those who realize only later in life that their congenital disorder is killing them and must be dealt with have tons of baggage they must also deal with.
Ironically, those who have travelled lightly through life, whether by choice or because of psychological difficulty, might not be in any better shape to change sex than those weighed down with baggage. Or rather, they might not be in any better shape to live a post-correction life. Some have never learned to love or to share intimacy. Some have never learned to live! That can cause other kinds of difficulties.
Changing sex later in life is unfair to everyone. It's unfair to the one changing sex, unfair to parents and family, and unfair especially to spouses, partners, and children. Coming to the truth after living a lie will do that. But whether that lie was conscious but suppressed or hidden beneath layers of social and physical pressure, it still has to go. Someone, perhaps many people, will suffer pain and heartache. But at base, it's still a birth defect, and dealing with it, however freighted with baggage, should be seen as a medical issue before anything else.
Problems happen most when the person neither fishes nor cuts bait. Living in between or trying to have it both ways just causes more pain all around. Better either to fix the birth defect, quickly, or to suffer in silence.
If you were born transsexual and become aware of it early in life, deal with it then. As early as you realize you must deal with it, do so. Don't wait. Don't avoid life; don't cope; just have the condition treated, just as you (or your parents) would a cleft palate or clubfoot. Don't think it's going to go away or be cured on its own. That strategy has never worked.