Also, even if it's true that all masters have put in 10K hours of deliberate practice, this is not equivalent to the idea that anyone who puts in 10K hours of deliberate practice can become a master, nor is it equivalent to the idea that anyone can become a master at anything (or anything physically plausible) with 10K hours.

This being said, I still believe (without evidence) that putting in some deliberate practice on whatever you care about is a good idea.