What does non binary mean ffs. Who is 'binary'?
(apart from Barbie, obvs).
It varies.
Some people id as non binary because they have body-based gender dysphoria such that they want treatment, but don't want to id as, the gender they would be medically be transitioning towards.
Some (but by no means all) intersex people id as non binary
Some people who id as non-binary wouldn't feel accepted/as if they pass as either a man or a woman, because they have a very androgenous appearance, or can pass as a man and woman in different circumstances (but not everyone who experiences this ids as non-binary).
And probably lots of non-binary people are just trying to navigate their place in the world the best they can.
And others would describe themselves as having a specific kind of gender identity.
Some non-binary people have always existed (even if they didn't use those specific words), and the concept that that is a way that you can id has only really happened in the last 25 years - beginning with radical queers in the 90s. I do think that part of the reason why some people id as non binary is because of a different way of looking at the world that's developed since then, and I've certainly come across people who pretty much say they must be non binary purely because they don't perfectly fit a gender stereotype, or who seem to have confused the concept of gender identity for personality, or politics or being a bit punk for identity (btw i'm partly talking about my younger self here). I also think there are some issues where non-binary people's needs and women's needs clash (especially where people try to be accommodating so they look inclusive but do it on the cheap and without much thought).
Whatever my concerns though, its clear that if half of the people in that survey are non-binary (and not all of the non-binary people id as trans), that non binary people experience a lot of shit - whether its specifically because of their non-binary identity or trans status, or because of their appearance or way of being (which would be the same regardless of identity), or whether the shit happened earlier in their life and contributed to them iding as non-binary. So its not something that can just be dismissed.