If you did 10,000 hours of dedicated guitar practice you absolutely would be one of the greatest guitar players of all time.

It's just an incredibly monumental task. 1. People don't understand how much time that actually is. It's 416.67 days....nonstop. If you take out 10 hours a day for sleeping, eating, and other basic human necessities and did nothing else but practice your craft for the other 14 hours in a day it would be 714.28 days to achieve the 10,000 hours. Then you have to contend with the fact that your brain physically won't let you concentrate for 14 hours a day, every day in a concentrated state practicing something...Let's be generous and say that it's possible for someone to do 4 hours of dedicated practice daily (which would still require many significant breaks to maintain concentration so it would actually take more like 6-7 hours to practice 4). It would take you 2,500 days of doing dedicated practice 4 hours every single day with no days off to achieve 10,000 hours total. That's basically 7 years of your life doing absolutely nothing other than existing and practicing your craft. 1/10th of an average persons life.

I also cannot oversell enough the difference in just doing something for 10,000 hours and doing dedicated practice to get better at something for 10,000 hours. Dedicated practice is basically the equivalent of sitting down and writing computer code. It requires an extreme level of concentration and pushing themselves.