Just sharing my own experiences. I am someone who did do exactly that, bad childhood and I couldn't stand myself nor people anymore.
It made me feel better to live in a fantasy world, as some made up fictional creature. I felt stronger, and it got me through life when nothing else did.
It also messed me up at the same time.
I didn't know about therianthropy at the time. And this obviously was coping, even if I would have never admitted it during this time.
I found out about being a therian much later as an adult, and I really struggled with accepting the species and constantly feared that I'm being delusional again.
I've gotten better about it but this required work. I still am not too keen on it.
It also doesn't explain all the stories that exist from my mom and grandma. I've always had a thing for animals instead of people. Even as a toddler. I was always drawn to animals and the other way around. I learned to walk first - then decided all fours is faster.
I played in nature, acted like an animal, or spend time with animals instead of kids. I also hated sweets/artificial foods of any kind for a long time but otherwise was open for anything. This stood out already...
I was often bullied in school for acting like an animal...yet it felt right. And there was no way I was giving it up. Even if that would have made things easier and I knew this much even back then.
For me therianthropy never had any comfort to it so far. I embarrass myself with mental-shifts out of my control. (Even before knowing about it all.)
And I'd say I've been born with the trait. Because of the people who knew me from as young as possible.