Many people here are saying the "10,000 hours rule" is a myth, and while I wouldn't disagree with them it's a little more nuanced than that. Gladwell is a populariser, and simplified the research of Anders Ericsson [1] into a catchy soundbite.

Ericsson describes "deliberate practice". That is, to become an expert you must "work on high specific tasks assigned to overcome weaknesses, and you would have your performance monitored carefully for further improvement" [2]

[1] https://psycnet.apa.org/record/1993-40718-001

[2] https://www.ysamphy.com/anders-ericsson-deliberate-practice/