For me, it was the content. I stopped playing piano at 14, because my teacher really wanted me to play classical. Not a fan.

I came back to piano later by myself when I wanted to play video game music. Then I wanted to play stuff from movies, pop songs, etc. I started watching interesting videos on reharmonization and tried that on some pop hits to interesting effect. I wouldn’t say I “stopped” completely, but my relationship with the instrument is completely different than it was when I was taking full time lessons growing up. I’m at the point where I might take it up again, but I would have specific goals in mind now.