You don’t need a piano teacher.
I have learned classical guitar, calligraphy, and drawing on my own, without a teacher. There’s no reason piano should be any different.
Yeah, I’ve taken piano lessons, so I can never claim to be completely self-taught on piano, but still, I’ve learned a lot of piano on my own as well.
On the other hand, you do need a piano teacher.
Learning doesn’t happen in a vacuum. It requires books, videos, other people, your own experimentation, and all kinds of input from your environment.
But you don’t need a piano teacher. It’s ridiculous to think that you do.