I see your excellent point about it being like a sport or other activity that takes practice and doing to become good at it and if that is your choice, an okay thing to do.
The problem with younger people though is not yet having tried very many things or gotten enough all-around education yet? That can lead to not having a good "base" and being lopsided
My husband is an engineer and my degrees were in sociology and history. He and I have a fun discussion about what courses we had to take in college, he didn't think he gained anything from his English literature courses, thought they were stupid for him to have to take. But it is often pointed out how poorly engineers write/communicate (my husband does both extremely well) and that causes problems for them as they get further in their career.
http://neptune.spacebears.com/opine/engineer.html
A soccer player doesn't just play soccer; he does drills and exercises his body in other ways. Look at football players and their conditioning exercises? Where are your conditioning exercises so you learn to communicate better with your co-players on your team? No, you probably don't need a "teamwork" course, but working on teams in school, doing a science project together and talking to people face-to-face would help you with your game playing. Learning to see patterns, in "real" life, in nature, human relationships, art, music, etc. would help you find the "enemy" or solve the problem faster.
Look at a group of soldiers in real life; they don't just do practice raids but also have school work and discipline, keeping their weapons cleaned and in order, their shoes shined and beds made. They may not enjoy doing those things but do them because it helps them discipline themselves, helps them learn to focus and pay attention to details and learn the patterns that make things work smoothly.
I think there is a lot you are missing by playing games for most of your time. When you are at school, you do not concentrate on just one course, don't sit in just one classroom do you? The routine of school and how it is laid out is not just to frustrate you because you'd really rather do something else and adults know that so try to thwart you

You can use that routine to your advantage in life.
I'm 61 years old and daydreamed my way through trig in 11th grade. I have a great imagination and creativity oozing out of my pores. But that's not enough! I got to college and took the "easiest" math I could get away with and 10-15 years later, when computers were beginning to get really big, I was screwed because I hadn't paid attention in math. Who knew? I hadn't been present for my life as I was living it; I was in my imagination instead, inventing "stories". Yes, I'm a good writer (which is not just default creativity either but 10+ years practice/hard work) and I have all the aptitudes for computer programming but I failed to pay attention in that part of my life and it was too late to get that back. I could have had an interesting-to-me AND paid well job but had to settle for a lesser one that just paid the bills.
I'm not unhappy with my life and choices but just pointing out that I wish I had paid attention in all of my life instead of escaping to "easier" or more fun ways of being as a teenager.
Ask people who played sports/basketball most of their teen years but didn't make professional teams what they "became" as adults? What choices are you working toward as an adult? You can't design games unless you have the math, science (physics) and "art"/design background and that takes a lot of work, now, not later. You miss what's going on "now" by doing X and you can't get now back so maybe later you can choose Y or Z. The games and those who play aren't going to go anywhere and you're good enough that a couple hours a day would keep you in fine form! Choose something else to help you in the future with the 3-5 other hours?