Its difficult, probably impossible, to 'teach' binary people, especially those that have acquired years of stories, procedures, steps, formulas, and guidelines - libraries of binary culture, including transitioning information - to explain that in non-binary cases, those formulas and 'success' stories wont work. I don't think that I have ever changed anyone's belief before. Those already tolerant and friendly remain so. Those that believe in one truth have never changed their opinion.
Its my opinion you can either push it aside and ignore, be friendly and forgiving, try to instruct, or strike back on the offense.
I don't know what your fits your personality best. Or the personality of the person replying and reacting. Lately, I choose the later. To me, the other three haven't worked.
When they have thousands of examples that binary thinking does work, and no examples (which was there but they probably ignored in their construction of a library collection), I don't know if anyone could ever say, "look at these 10 people, or 50, or 100."
The thousands will always trump those rare exceptions, especially when less documented, marginalized, and less likely added to their library of transition knowledge.
Here is possibly one example of facial feminization regrets: (i don't know if this still holds true)(or if I have the whole story correct) Melanie Anne Phillips wrote in her site a few years ago how she had first posted a pre facial feminization frontal nude photo including her face on a website of GG women that is rated by viewers. She was rated high. With some hesitancy, she got the surgery, hoping to increase her femininity. She had regrets when her score was much lower after the facial feminization, when posting it again when fully healed and looking natural, leading to depression. Her face was more feminine, but somehow was now less attractive. She wanted to be more attractive.