I realize it is not what has been touted, but I always took the "10K hours" thing to mean, "it takes 10K hours to reach your potential". That is still a
way too convenient round number, but good enough for a rough estimate.
But it has a flip side: "after 10K hours, that's about as good as you're ever going to get". I've easily got 10K hours on the guitar, but I'm no Jimmy Page, nor will I ever be. 10K hours of running? 40 years, carry the one...yeah, probably. Look through my comments, see anything about the Olympics? A few wins at some regional-level races is all I'm ever going to get.
On the other other hand, if you put the time in, you might not become Jimmy Page/Bobby Fischer/Usain Bolt, but I am convinced you'll get competent at whatever you pursue. No musical talent? Bah, sit down for a half hour a day of real practice for a month, tell me how little "talent" you have.