My teacher's ability to help me learn what I wanted to learn made me so invested in piano as a kid. Many kids don't stick with music because (IMO) they can't find a way to enjoy it or be invested in it. For me, what I enjoyed happened to be Beethoven, but at other times I just wanted to improvise various modern songs. (Which can be as simple or as complex as you want, but a lot of classically trained teachers can't/won't/don't teach improvisation.)
Technique and theory only get you so far. Being able to emotionally invest in your playing is what sets musicians apart, imo. And as you're growing as a musician (even when you're a kid), you're going to sound like shit if you just try to monotonously follow the instructions. I'm not sure enough music teachers get the importance of being personally and emotionally invested in the moment as you're playing. (One-buttock playing is a good word for this: https://youtu.be/r9LCwI5iErE)
The choice of what you want to play is pretty important in keeping you invested.
I tell people: you wanna play Rachmaninoff's Piano Concerto? Go fucking play it. I mean you're not gonna play it well, even some world-class pianists can't, but if it gives you pleasure to try, and motivates you to play piano, that's fine. If you're gonna be a professional pianist, or you're a student at university, it's an entirely different matter. Some people are just hobbyists, or they want to be composers and learn piano to help compose (which is an extremely important core skill for a composer). Those people can just sit down and play whatever they want, along with things that are at their level that they can perfectly play.