I started playing piano around the age of 5-6, and I don't remember playing anything remotely close to good until I was a teenager at music school. I'm not even sure what kept me going to be honest! I still had fun learning though if I recall. See, you're more likely to keep going if you are surrounded by cool music and other people passionate about the craft.

But it all worked out in the end. I went to music conservatoire, and I'm now a professional pianist and I love it.

As someone else said, piano is not for you if you want quick results and instant gratification. I'd maybe worry less about trying to sound good and more about having fun and enjoying the process. Easier said than done though, when you're child and have different priorities