"How often do you think people sit there and admire their own tattoos? It's a way to express myself to others."

You don't need to justify why you have a tattoo to someone. You wanted to get a tattoo for yourself, not necessarily for others.

It's a way to express yourself.
Maybe this is a bad example but, I have posters in my room of different anime and game characters, but I can't see. I have them here around my room, because I like watching anime, and playing games.
I have a few arcade fightsticks for playing fighting games, and I got a guy to make custom art to put on the front of the fightstick. The art is of my favorite character in a game I play. I can't see it, but others who are around me can.

I would have said "for the same reason some people tattoo their backs. I like it and I know it's there."

Honestly

"Because I wanted to."

"Why do you have a brain? You can't even use it!"

I'm sorry you encountered such ignorance :(