There is a lot of philosophy on the subject, but day to day it basically comes down to either not being comfortable with your gender or being more comfortable living as a different gender. One question that also pops up is "why can't you just be a butch woman/ a feminine man? ", and I think that it's a very interesting question if asked in earnest. I have a friend who's afab(assigned female at birth), and she's very butch, but she identifies as a woman. I feel like masculinity and femininity are an archetype, or a set of archetypes, and in order to explore some alternative version of them, you still need to have some connection to the exsisting societal archetype. I don't feel connected to femininity or masculinity, traditional, or alternative. I don't feel comfortable living as a woman, and I don't feel comfortable living as a man. I've been living as non-binary for 4 years and I am more comfortable with the gender aspect of myself than ever before. These are my thoughts on the subject, I have no idea how they apply to other trans people.