I'm going to deviate slightly from others. Attention seeking can play a big role, but it's not the only answer or the only component (but don't be fooled, chicks who do it IRL want attention).
Back in the day when WOMEN POWER! and "Guyz women are so beautiful im cry" post were everywhere, there waa a big surge in they themism in young women. Why? Because women are:
And young women, teens especially, couldn't feel like they could measure up to it. It doesn't matter if they were conventionally or unconventionally attractive or not, if they actually were smart or not, if they were strong or not:
it was how they felt. A lot of arrested development women and outsiders into their 20s and feel that way, usually dropping by their early 30s since they find places to belong by then in the world or are over their identity struggles. It is and was a way to get out of feeling as much of a failure because you don't have confidence. You suck, you don't measure up, and you don't feel like a man, so the unconventional third option felt more like a group you could jump into and fit in with.
Many of these women also struggle with things like social rules, whether it is because they have a mental illness or disorder. Disorders like Anxiety, autism, ADHD, and others can make you feel physically apart from your body and like you're not attached to it. The "my body just does things" feeling, or a spirit piloting a meatsuit. Other disorders they face can be image related like eating disorders, as well as cluster B (attention seekers/no solid identity). Not all of these people are bad: these young women are just struggling and can externally put pressure on themselves. Women who I know on the internet who go by they/them usually don't do it IRL: they just know and are resigned to it. They don't want to be judged, but can't change it. It's not healthy to just do it on the internet either, but you get a lot less annoying people that way.
They/them also is an identity taxon. People like cosplayers and theater kids who love dress up end up becoming that kind of retard they them because it's cool in their group and they feel a spiritual woo connection to it because omg I dress up as either gendie!!! It's dumb but that's theater kids.
There's also a lot of trauma and abuse victims who have say a horrible mother or other female role models and really don't want to think of being female because of that. Or they're trying to be sexless and sexually unappealing because they have sexual trauma and hate it. They're not as common, but it clicks when you find a few.
TL;DR: I think a lot of male farmers forget women can feel just like this too, they just sometimes have different bad habits of cope:
I'm on the outside
I never could sit still
I never was too hip
I never caught the ride
I'm on the outside
I'm on the outside, I'm on the outside now
This is where it all begins on the outside looking in
Looking in
At you
I'm just an alien through and through
Tryin' to make believe I'm you
Tryin' to fit
Just a stranger on the outside looking in
Feeling like a fucking loser who doesn't get others and
must be something else because you feel like you suck so much is a universal human experience shared by many, many people. Not everyone feels it, but it is rare not to have a moment.