A lot of gender dysphoric people don’t transition.
In fact, based on the anecdotal evidence of people I’ve interacted with, I’d guess that only about half of gender dysphoric people transition.
Note that by “gender dysphoria” I mean not the various limited definitions invented by trans people on the Internet, but the actual, clinical definition in the DSM-V:
A. A marked incongruence between one’s experienced/expressed gender and assigned gender, of at least 6 months’ duration, as manifested by at least two of the following:
1. A marked incongruence between one’s experienced/expressed gender and primary and/or secondary sex characteristics (or in young adolescents, the anticipated secondary sex characteristics).
2. A strong desire to be rid of one’s primary and/or secondary sex characteristics because of a marked incongruence with one’s experienced/expressed gender (or in young adolescents, a desire to prevent the development of the anticipated secondary sex characteristics).
3. A strong desire for the primary and/or secondary sex characteristics of the other gender.
4. A strong desire to be of the other gender (or some alternative gender different from one’s assigned gender).
5. A strong desire to be treated as the other gender (or some alternative gender different from one’s assigned gender).
6. A strong conviction that one has the typical feelings and reactions of the other gender (or some alternative gender different from one’s assigned gender).
B. The condition is associated with clinically significant distress or impairment in social, occupational or other important areas of functioning.
Now, some of the gender dysphoric people who don’t transition really ought to transition. I am certain every trans person has had the experience of talking to a friend and wanting to shake them and say “YOU’RE A GIRL! YOUR PROBLEM IS THAT YOU’RE A GIRL AND IF YOU STOP THINKING YOU’RE A BOY THIS WILL ALL BE FIXED!”
However, I’ve met a lot of gender dysphoric people who wouldn’t be served by transitioning. Some of them have practical objections. For instance, I’ve met people who find that their gender dysphoria is mild enough that they feel treating it would be outweighed by the transphobia they’d face. Other people experience physical dysphoria that it’s not currently possible to fix: for instance, they may feel dysphoric about not having erections, but they’d also feel horribly dysphoric about having chest hair.
Another very common category is people whose experienced gender is “I do not want to see or be seen by gender”. They may feel deeply dysphoric in highly gendered spaces like a Girl’s Night Out or Women in STEM group. However, transitioning to the other binary gender would give them a different set of highly gendered spaces, and presenting as nonbinary means that your gender is quite unusual and therefore the most salient thing about you to most people you meet. For this reason, they often wind up identifying as cisgender.
I think trans communities on the whole need to be more aware of the existence and needs of gender dysphoric non-transitioning people. Our gender theory should allow space for people who are gender dysphoric but don’t want to transition. We should let them talk about their experiences without immediately jumping in with “so, you’re trans, though.” This will help both gender dysphoric people who don’t want to transition and gender dysphoric people who’ll end up transitioning– being trans is scary! It’s a lot easier when you can articulate your experiences without committing to the huge life step of transitioning.
Furthermore, we need to be conscious of competing access needs. Certain recommendations to make spaces more accommodating to trans people– “everyone go around the room and state your name and pronoun!”, “ask everyone you meet what their gender is!”– tend to bring gender into the forefront. That’s unwelcoming to non-transitioning gender dysphoric people, who have to misgender themselves. And it’s really unwelcoming to “I do not want to see or be seen by gender” people, because it’s suggesting that one of the things that causes them gender dysphoria should be socially mandatory. In general, I think we should be cautious before making a big deal out of people’s genders, and if we do offer an ability to opt out (for instance, making it clear that people do not have to give a pronoun if they don’t want to).