So this one time I accidentally a truscum
I decided to write a post about what it was like for me to grow up a trans girl (well, somewhere between "girl" and "no gender at all"), and I threw in some comments that basically said "all trans people are like this" and referred to specific experiences.
Several good friends said "No, it was not like that for me." Two friends were actually upset and invalidated by what I had written. So I took it down and apologized.
This was in 2008, and a lot of the stuff in that post I developed further (and others have developed similar or more often better ideas than what was usable from that post).
It was my mistake, though. I said something about all trans people that was not true about all trans people. Faced with a reality that did not match my theory, I simply abandoned the theory that was demonstrably false.
People are more important to me than ideas that turn out to be wrong, no matter how much I liked the idea.