>>60990I have a lot of trans friends and I talk to trans people regularly.
From what I'm told the desire to transition comes from a sense of dysphoria. People don't feel comfortable in their own skin and they just feel more comfortable and at ease when they act and dress as someone of the opposite sex. Some people claim to feel their entire lives and some people claim that it's just something that started bothering them when they hit puberty or afterwards.
There's also a common theme among many that they're either failing to live up to the ideal of their original gender. Like you'll see a lot of people who end up transitioning MtF later down the line act super masculine and try to be as manly as possible and they end up making themselves miserable because it's just not what they want to do.
In the end these are just generalizations based on observations I've made. You're much better off asking individual trans people if you can find some who are willing to talk about it. A lot of them are pretty chill about it, so it's a bit easier than you might think.