This is a good question which cannot really be provided with scientifically proven reasons, so we can only look at possibilities.
From personal experience as a therapist, anecdotally I can say that with some people, the meme would not be complete. With these people the situation would be
I didn't think I would get this far so quickly
and that could be a key point with many others.
When planning for the future, do you plan for things you know you will reach very soon or do you include those points where you cannot envisage getting to right now?
Forward planning can be different from person to person, and if you haven't planned for a particular eventuality, how do you know what you want to do, let alone how you should do things?
The comment at the bottom of your image:
I have managed to change my name and gender on ALL of my legal documents! So what's next?
can be a comment of surprise, and maybe despair; or it could be:
Good! I have that out of the way, now do I have to do anything else?
The processes involved with identity change can be daunting and therefore some choose to take things a step at a time rather than planning the whole process before carrying it out.
Is the person aware of all the things they need to do?
Can they cope?
Do they have the support of professional organizations to help along the way?
Do they have support from friends and family?
All these things and more will affect how the person will be dealing with the situation.