I'll just speak from my own experience from MS/HS Ball.
I played ball from 5th grade through 11th and quit before my senior year. I never have regretted it, I am only a freshman in college so I might later but as of now, not once. Basically my life in HS was ball then school not the other way around. It was "open gyms" very strongly (almost mandatory for non-football players) encouraged by the coach. Practices from the 1st day of legal practices until late Feb. - Early March. Then we got about 2 weeks off before off season lifting started. Do that for a bit, then its the summer ball circuit where we would all be on the same team since none of us were good enough to be play college ball so we just worked on the HS plays, etc...
It got to the point where one day I specifically remember during the summer before my senior year started. It was our 1st practice of the summer and I woke up, and took a shower. I remember when I got out of the shower I looked myself in the eye in the mirror and said, "Do I want to give 100% this year?" The answer? "No" So I drove to practice, turned in my jerseys and told coach that I respected all that he had done in making me a better player and a better man but that I couldn't give 100% this season so I had to step aside.
Again, this is just my story. For every kid it is different. This was just an 18 year old guy's point of view.