I think there are many reasons and many different ways for gender dysphoria to develop for LGB people or to exist as transsexuals. Stories from detransitioners, lesbian trans men and gay trans women all point to homophobia and abuse as the culprits. And historically, crossdressing and transvestism was a subculture for LGB people. Even further back in history, a lesbian may pass herself off as male in society in order to be with or "marry" her female partner. Gay men excommunicated from society would sometimes resort to crossdressing prostitution to survive. TRAs love to point to cultural "third genders" as a gotcha, but those "third gender" categories applied to homosexual or bisexual men as a way to other them from society (nevermind that there were no categories for women because women were already considered othered). To this day, medical transition and chemical castration are mandatory conversion therapy for convicted homosexuals in various countries (the most high-profile case being Iran). There is a precedence for this in Western countries as well, as happened with Alan Turing. So I understand why LGB transgenderism and gender dysphoria exists.
But if heterosexual transgenderism is real and not a recently developed fetish/trend in 1st world countries, then where has it been? Where were the transbians fighting for gay rights and women's rights? Where were they when women were fighting for the vote? Where, in the present day, are the hoards of married heterosexual middle-aged women coming out as trans men and complaining their husbands and kids won't accept their obsession with gay male culture? Where were all these "gay" trans men when actual gay men were getting hate-crimed dying en masse? I'll tell you where, these people were all typical conservatives in heterosexual marriages, and from the way they talk, were probably hate-criming and discriminating against LGB themselves. (And no, a 18th century example of a woman passing herself as a male in order to pursue working in a male-gatekept profession does not a trans man make).
I concede that at least from what I've seen on social media, some detransitioned heterosexual men and women developed GD and medically transitioned due to child sexual abuse. But the argument from TRAs is that these are not "real" trans people with "real" dysphoria anyways.
Prove to me it's not a privileged fetish and new-age trend.