Since we're all free to discuss here, I'll share that anecdotally, I have found universally that the ones that "transition back" are universally female at birth. This would line up with a few things. First, it lines up with the idea that gender as a social construct, that is, the aspect of gender made by society and not predetermined biologically, could confuse someone like your body insecure butch lesbian friend to feel the need to "correct" herself, as you say. The idea that certain roles correspond to certain genders combined with, as you call it, a "climate" that encourages people who identify with roles assigned by society to a gender that doesn't correspond to theirs to accept the idea that not everyone's psychological gender corresponds to their biological sex, can understandably cause some confusion. The confusion lies in the fact that while gender has an aspect to it that is a social construct, there is also an aspect to it that seems, according to recent science, to be biological. Nature vs nurture and all that. Your butch lesbian friend does not identify with society's construct of femininity and roles and customs appropriate for females. Nor should she have to, as those societal constructions are bullshit. However, if there is also a biological aspect to it, which you would naturally expect seeing as male and female brains are in fact constructed with minor differences, then you cannot and should not attempt to deconstruct that aspect. Until we are able to parse out what of gender is socialized and what is biological, confusion is bound to happen and we should recognize that confusion for what it is and not encourage it.

But then, you may ask, what of the males? Can they be confused? Certainly they can, but they are more likely to be sincere, which brings me to the second thing that my anecdotal experience lines up with, which is science. The current scientific evidence suggesting that gender identity has a biological aspect to its origin suggests that the mechanism is in prenatal development, and has to do with hormones. Specifically, that during development of the brain, hormones determine its formation and differentiation between male and female brains, and that if the wrong hormones are present in the developing fetal brain, the brain can develop in a way that contradicts how the genitals are developing. This could literally create what amounts to a female brain in a male body, or vice versa. The consequences of this mechanism are very telling though, in that they would suggest that a birth sex discrepancy should exist in transgendered individuals, since the main opportunity for this hormonal imbalance during development is likely to be the mother's hormones getting into a male baby's brain, a fraternal sister fetus' hormones getting into her brother's brain, or both, for male birth sex fetuses, while the main opportunity for female birth sex fetuses would only be the fraternal twin brother's hormones getting into her brain. There would be significantly less opportunity for the creation of a female brain in a male body through this mechanism. The other mechanism involves genetics that affect androgen receptors (which would create MtF trans babies) and that affect the gene which acts on progesterone (which creates FtM trans babies), but this would create more MtF than FtM as well, due to the prevalence of these genetic abnormalities. This all plays out well in the data we have on transgender demographics, which suggests that the ratio is at least 3:1 MtF(male birth sex) to FtM (female birth sex). This ratio could be even more lopsided, since there seems to be a bit more stigma to being MtF so that side could be under reported, while scenarios like your butch lesbian friend mean that the FtM side could be overreported.

I too have seen instances like your friend, but they didn't act as a tipping point for me because I've seen compelling scientific evidence that this is real, as well as plenty of anecdotal instances of individuals that suffered greatly for their transgendered status yet did not change. I could chalk some of those instances up to psychological disorder, but not all. Much of it seems to be genuine gender dysphoria. From my experience, the earlier people are sure (even if they hide it for awhile), the more likely it is sincere and not something they'll reverse down the line when they realize they just confused a mismatch of gender roles with a total mismatch of gender. All that besides, even if some transgender identifying individuals are not sincere or merely confused, if a portion of them are not confused but have a hard, biological origin to their feelings, then they cannot help it, and do not deserve to be punished with the refusal of society to accommodate them just because some within their community are just confused and need a different kind of help. Really, I find it difficult to imagine how you could fail to see the parallels here between this and when the gay rights movement received pushback from those claiming that homosexuality was a choice or a psychological disorder. They face firings, harrassment, bullying, homelessness, denial of essential goods services like the housing market and medical care, increased targeting from law enforcement, and abuse and violence. They face all this and yet they do not change. This is clearly not a choice. Science suggests that it is not a psychological disorder, but is biological in nature. So I take their claims seriously and don't dismiss them.

That doesn't mean I have no right to criticize the movement. I criticize the feminist movement, the gay rights movement, and movements for non-white races, when I see something I think is deserving of criticism. Disgusting, nonsensical claims like the idea that genital preference transphobic is something I'll enthusiastically criticize. I don't need to dismiss the validity of an entire movement to criticize it.

In regards to your question to the other guy about the I in LGBTQI, just to give you a bit more primer on it, it stands for Intersex, and refers to purely biological differences in sex that prevent an intersex individual from being identified as male or female. You may look at them and think they are one or the other, but you would be wrong, objectively. They do not meet the criteria of biological science to be classified as one of the two sexes. They may have genitalia that are not a penis or vagina, they may have sex chromosomes that are not XX or XY, they may have a penis or vagina but the rest of their reproductive system might not match (vagina and uterus but testicles instead of ovaries, penis but no testicles and a tiny womb instead of a scrotum, the possibilities are endless). Since this isn't one phenomenon but rather myriad biological phenomena, intersex is not a third sex, but simply an umbrella term to describe all people for whom the two sexes do not apply. They are included in the LGBTQI abbreviation because they are a marginalized community as well, and because of the interaction of their intersex status with gender. I mean really, how can you not accept that gender is a psychological concept separate from sex once you encounter the concept of intersex? They have no sex, but they still have a gender, and it's in their head, and tends to be whatever they feel closest to. Sometimes they identify with neither binary gender, and choose some kind of in between third option like non-binary, genderfluid, or some such. I can hardly criticize them for that since they objectively are not male and objectively are not female, scientifically, biologically, so as far as I'm concerned there is no legitimate way to question their gender identity. From there, it's not a huge mental leap to think that within the scope of human biological and psychological variation that some individuals might be effectively identifiable as being of male or female sex, but might have a predisposition to identify with a gender that doesn't match that sex for any number of biological or psychological reasons. So again, while I criticize the trans movement at times, it seems silly to dismiss them entirely, or to, as some people do, dismiss the concept of gender as a psychological aspect of a person separate from their biological sex.

Chimera doesn't necessarily mean two species, at least in the scientific sense. It means two distinct genotypes. Genotypes meaning a set of genes. If a human being is a chimera, it's probably because something weird happened to their twin in the womb. Sometimes a human chimera just has two blood types, theirs and their sibling's. Other times, a human chimera will have their whole body, but also have their opposite sex sibling's genitalia. Sometimes, a mother will give birth to children that don't have any of her DNA, because one of her eggs was made with DNA from the mother's twin who was absorbed into her when she was in the womb. It's absurdly, insanely rare.