You are just getting started. I've only now felt like I've hit the wall, and I'm at about 300 hours.
What rank? I've felt a huge difference in competition at 2500+. 10k to 5k wasn't bad, but the moment 2500-3000 and consistent 300pp plays just to maintain it hit I felt the burn.
generally 100k to 200k if you're talking about leaderboard position.
I don't grind PP, Never got into that scene. I've just been working on songs, and as it stands I can't crack Expert+ Ghost, Light it up, and Spin Eternally. That seems to be my limit.
Well say goodbye to your life! I'm hundreds of hours in now and play 4 hours a week minimum.