Gender fluidity

I don't know why I am so turned off by the concept of gender fluidity. Maybe because I don't understand it viscerally and cannot relate. 

I don't want to be two people, I want to be one and when someone talks about two personas I reject it outright.

I have always thought about my situation as someone coming to terms with who they are progressively over a lifetime but always being the same person. I don't have two people living in me and I behave the same way all the time. 

Young transgender people don't need to live for years in one presentation and then switch. They won't be forced to reconcile a previous life with a new one. They just have one.

If I were young today knowing what I know I would simply transition and be done with it.